| Schedule of Available-for-sale Securities [Line Items] |
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract] |
Available-for-sale Securities, Continuous Unrealized Loss Position, Less Than 12 Months, Fair Value | Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses | Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value | Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses | Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value | Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses |
2007 | | Debt and Securites Other than Mortgage-backed Securities [Member] | US Government Agencies Debt Securities [Member] | 0 | 0 | 0 | 0 | 0 | 0 |
US States and Political Subdivisions [Member] | 328,000 | 8,000 | 9,857,000 | 33,000 | 10,185,000 | 41,000 |
US Government-sponsored Enterprises Debt Securities [Member] | 1,384,000 | 15,000 | 2,081,000 | 33,000 | 3,465,000 | 48,000 |
| Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] | 148,537,000 | 593,000 | 789,643,000 | 11,834,000 | 938,180,000 | 12,427,000 |
Mortgage-backed Securities, Issued by Private Enterprises [Member] | 0 | 0 | 304,440,000 | 8,533,000 | 304,440,000 | 8,533,000 |
Mortgage-backed Securities [Member] | 148,537,000 | 593,000 | 1,094,083,000 | 20,367,000 | 1,242,620,000 | 20,960,000 |
Other Debt Securities [Member] | 0 | 0 | 218,981,000 | 1,012,000 | 218,981,000 | 1,012,000 |
Major Types of Debt and Equity Securities [Domain] | 150,249,000 | 616,000 | 1,325,002,000 | 21,445,000 | 1,475,251,000 | 22,061,000 |
2006 | | Debt and Securites Other than Mortgage-backed Securities [Member] | US Government Agencies Debt Securities [Member] | 1,097,000 | 4,000 | 2,253,000 | 36,000 | 3,350,000 | 40,000 |
US States and Political Subdivisions [Member] | 8,738,000 | 32,000 | 14,887,000 | 146,000 | 23,625,000 | 178,000 |
US Government-sponsored Enterprises Debt Securities [Member] | 155,494,000 | 536,000 | 67,310,000 | 694,000 | 222,804,000 | 1,230,000 |
| Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] | 150,042,000 | 1,276,000 | 1,470,154,000 | 40,937,000 | 1,620,196,000 | 42,213,000 |
Mortgage-backed Securities, Issued by Private Enterprises [Member] | 41,643,000 | 923,000 | 315,121,000 | 7,000,000 | 356,764,000 | 7,923,000 |
Mortgage-backed Securities [Member] | 191,685,000 | 2,199,000 | 1,785,275,000 | 47,937,000 | 1,976,960,000 | 50,136,000 |
Other Debt Securities [Member] | 0 | 0 | 318,836,000 | 6,115,000 | 318,836,000 | 6,115,000 |
Major Types of Debt and Equity Securities [Domain] | 357,014,000 | 2,771,000 | 2,188,561,000 | 54,928,000 | 2,545,575,000 | 57,699,000 |