Fair Value Measurements (Details) (USD $) In Thousands	Jun. 30, 2011	Dec. 31, 2010
Fair Value, Measurements, Recurring [Member]
Investment Securities, Available-for-Sale:
Available-for-sale Securities, Fair value	$ 1,472,743	$ 1,522,911
Investments carried at fair value
Other assets held at fair value	45,920	41,309
Total assets	1,518,873	1,564,442
Liabilities:
Other liabilities held at fair value	78,184	78,287
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Investment Securities, Available-for-Sale:
Available-for-sale Securities, Fair value	520	263
Investments carried at fair value
Other assets held at fair value		0
Total assets	520	263
Liabilities:
Other liabilities held at fair value	0	0
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Agency discount notes [Member]
Investment Securities, Available-for-Sale:
Available-for-sale Securities, Fair value		0
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Agency callable notes [Member]
Investment Securities, Available-for-Sale:
Available-for-sale Securities, Fair value	0	0
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Agency debt [Member]
Investment Securities, Available-for-Sale:
Available-for-sale Securities, Fair value	0	0
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Agency MBS [Member]
Investment Securities, Available-for-Sale:
Available-for-sale Securities, Fair value	0	0
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Asset-backed Securities [Member]
Investment Securities, Available-for-Sale:
Available-for-sale Securities, Fair value	0
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Collateralized loan obligation
Investment Securities, Available-for-Sale:
Available-for-sale Securities, Fair value	0	0
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Corporate debt [Member]
Investment Securities, Available-for-Sale:
Available-for-sale Securities, Fair value	0	0
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Equity securities [Member]
Investment Securities, Available-for-Sale:
Available-for-sale Securities, Fair value	520	263
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Municipal Bonds [Member]
Investment Securities, Available-for-Sale:
Available-for-sale Securities, Fair value	0
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Non-agency MBS [Member]
Investment Securities, Available-for-Sale:
Available-for-sale Securities, Fair value	0	0
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | U.S. Treasury and agency securities [Member]
Investment Securities, Available-for-Sale:
Available-for-sale Securities, Fair value	0	0
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Warrants [Member]
Investments carried at fair value
Investment securities	0	0
Other assets held at fair value	0
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Investment Securities, Available-for-Sale:
Available-for-sale Securities, Fair value	1,447,825	1,510,384
Investments carried at fair value
Other assets held at fair value	45,290	41,309
Total assets	1,493,745	1,551,693
Liabilities:
Other liabilities held at fair value	78,184	78,287
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Agency discount notes [Member]
Investment Securities, Available-for-Sale:
Available-for-sale Securities, Fair value		164,974
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Agency callable notes [Member]
Investment Securities, Available-for-Sale:
Available-for-sale Securities, Fair value	124,990	162,888
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Agency debt [Member]
Investment Securities, Available-for-Sale:
Available-for-sale Securities, Fair value	56,964	103,430
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Agency MBS [Member]
Investment Securities, Available-for-Sale:
Available-for-sale Securities, Fair value	1,133,527	870,155
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Asset-backed Securities [Member]
Investment Securities, Available-for-Sale:
Available-for-sale Securities, Fair value	19,890
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Collateralized loan obligation
Investment Securities, Available-for-Sale:
Available-for-sale Securities, Fair value	0	0
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Corporate debt [Member]
Investment Securities, Available-for-Sale:
Available-for-sale Securities, Fair value	5,061	5,120
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Equity securities [Member]
Investment Securities, Available-for-Sale:
Available-for-sale Securities, Fair value	0	0
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Municipal Bonds [Member]
Investment Securities, Available-for-Sale:
Available-for-sale Securities, Fair value	0
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Non-agency MBS [Member]
Investment Securities, Available-for-Sale:
Available-for-sale Securities, Fair value	87,613	113,684
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | U.S. Treasury and agency securities [Member]
Investment Securities, Available-for-Sale:
Available-for-sale Securities, Fair value	19,780	90,133
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Warrants [Member]
Investments carried at fair value
Investment securities	0	0
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Investment Securities, Available-for-Sale:
Available-for-sale Securities, Fair value	24,398	12,264
Investments carried at fair value
Other assets held at fair value		0
Total assets	24,608	12,486
Liabilities:
Other liabilities held at fair value	0	0
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Agency discount notes [Member]
Investment Securities, Available-for-Sale:
Available-for-sale Securities, Fair value		0
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Agency callable notes [Member]
Investment Securities, Available-for-Sale:
Available-for-sale Securities, Fair value	0	0
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Agency debt [Member]
Investment Securities, Available-for-Sale:
Available-for-sale Securities, Fair value	0	0
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Agency MBS [Member]
Investment Securities, Available-for-Sale:
Available-for-sale Securities, Fair value	0	0
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Asset-backed Securities [Member]
Investment Securities, Available-for-Sale:
Available-for-sale Securities, Fair value	0
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Collateralized loan obligation
Investment Securities, Available-for-Sale:
Available-for-sale Securities, Fair value	20,446	12,249
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Corporate debt [Member]
Investment Securities, Available-for-Sale:
Available-for-sale Securities, Fair value	717	15
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Equity securities [Member]
Investment Securities, Available-for-Sale:
Available-for-sale Securities, Fair value	0	0
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Municipal Bonds [Member]
Investment Securities, Available-for-Sale:
Available-for-sale Securities, Fair value	3,235
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Non-agency MBS [Member]
Investment Securities, Available-for-Sale:
Available-for-sale Securities, Fair value	0	0
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | U.S. Treasury and agency securities [Member]
Investment Securities, Available-for-Sale:
Available-for-sale Securities, Fair value	0	0
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Warrants [Member]
Investments carried at fair value
Investment securities	210
Other assets held at fair value	0
Fair Value, Measurements, Recurring [Member] | Agency discount notes [Member]
Investment Securities, Available-for-Sale:
Available-for-sale Securities, Fair value		164,974
Fair Value, Measurements, Recurring [Member] | Agency callable notes [Member]
Investment Securities, Available-for-Sale:
Available-for-sale Securities, Fair value	124,990	162,888
Fair Value, Measurements, Recurring [Member] | Agency debt [Member]
Investment Securities, Available-for-Sale:
Available-for-sale Securities, Fair value	56,964	103,430
Fair Value, Measurements, Recurring [Member] | Agency MBS [Member]
Investment Securities, Available-for-Sale:
Available-for-sale Securities, Fair value	1,133,527	870,155
Fair Value, Measurements, Recurring [Member] | Asset-backed Securities [Member]
Investment Securities, Available-for-Sale:
Available-for-sale Securities, Fair value	19,890
Fair Value, Measurements, Recurring [Member] | Collateralized loan obligation
Investment Securities, Available-for-Sale:
Available-for-sale Securities, Fair value	20,446	12,249
Fair Value, Measurements, Recurring [Member] | Corporate debt [Member]
Investment Securities, Available-for-Sale:
Available-for-sale Securities, Fair value	5,778	5,135
Fair Value, Measurements, Recurring [Member] | Equity securities [Member]
Investment Securities, Available-for-Sale:
Available-for-sale Securities, Fair value	520	263
Fair Value, Measurements, Recurring [Member] | Municipal Bonds [Member]
Investment Securities, Available-for-Sale:
Available-for-sale Securities, Fair value	3,235
Fair Value, Measurements, Recurring [Member] | Non-agency MBS [Member]
Investment Securities, Available-for-Sale:
Available-for-sale Securities, Fair value	87,613	113,684
Fair Value, Measurements, Recurring [Member] | U.S. Treasury and agency securities [Member]
Investment Securities, Available-for-Sale:
Available-for-sale Securities, Fair value	19,780	90,133
Fair Value, Measurements, Recurring [Member] | Warrants [Member]
Investments carried at fair value
Investment securities	210	222
Significant Unobservable Inputs (Level 3) [Member] | Warrants [Member]
Investments carried at fair value
Investment securities		$ 222