| 2007 |
Schedule of Available-for-sale Securities [Line Items] | Available-for-sale Securities, Debt Maturities [Abstract] | Available-for-sale Securities, Debt Maturities, Amortized Cost [Abstract] | Available-for-sale Securities, Debt Maturities, Amortized Cost, Excluding Securities without Single Maturity Dates [Abstract] | Available-for-sale Securities, Debt Maturities, within One Year, Amortized Cost | Major Types of Debt and Equity Securities [Domain] | 157,319,000 |
Available-for-sale Securities, Debt Maturities, after One Through Five Years, Amortized Cost | Major Types of Debt and Equity Securities [Domain] | 82,633,000 |
Available-for-sale Securities, Debt Maturities, after Five Through Ten Years, Amortized Cost | Major Types of Debt and Equity Securities [Domain] | 217,192,000 |
Available-for-sale Securities, Debt Maturities, after Ten Years, Amortized Cost | Major Types of Debt and Equity Securities [Domain] | 116,415,000 |
Available-for-sale Securities, Debt Maturities, Amortized Cost, Excluding Securities without Single Maturity Dates | Major Types of Debt and Equity Securities [Domain] | 573,559,000 |
Available-for-sale Securities, Debt Maturities, without Single Maturity Date, Amortized Cost | | Mortgage-backed Securities [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] | 1,678,828,000 |
Mortgage-backed Securities, Issued by Private Enterprises [Member] | 312,973,000 |
Major Types of Debt and Equity Securities [Domain] | 1,991,801,000 |
Available-for-sale Securities, Debt Maturities, Amortized Cost | Major Types of Debt and Equity Securities [Domain] | 2,565,360,000 |
Available-for-sale Securities, Debt Maturities, Fair Value [Abstract] | Available-for-sale Securities, Debt Maturities, Fair Value, Excluding Securities without Single Maturity Dates [Abstract] | Available-for-sale Securities, Debt Maturities, within One Year, Fair Value | Major Types of Debt and Equity Securities [Domain] | 156,912,000 |
Available-for-sale Securities, Debt Maturities, after One Through Five Years, Fair Value | Major Types of Debt and Equity Securities [Domain] | 82,341,000 |
Available-for-sale Securities, Debt Maturities, after Five Through Ten Years, Fair Value | Major Types of Debt and Equity Securities [Domain] | 218,091,000 |
Available-for-sale Securities, Debt Maturities, after Ten Years, Fair Value | Major Types of Debt and Equity Securities [Domain] | 116,935,000 |
Available-for-sale Securities, Debt Maturities, Fair Value, Excluding Securities without Single Maturity Dates | Major Types of Debt and Equity Securities [Domain] | 574,279,000 |
Available-for-sale Securities, Debt Maturities, without Single Maturity Date, Fair Value | | Mortgage-backed Securities [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] | 1,684,471,000 |
Mortgage-backed Securities, Issued by Private Enterprises [Member] | 304,440,000 |
Major Types of Debt and Equity Securities [Domain] | 1,988,911,000 |
Available-for-sale Securities, Debt Maturities, Fair Value | Major Types of Debt and Equity Securities [Domain] | 2,563,190,000 |