Available-for-Sale and Held-to-Maturity Securities (Schedule of Amortized Cost and Fair Values of Debt Securities by Contractual Maturity) (Details) (USD $) In Thousands	Jun. 30, 2011
Debt securities, Available-for-sale, Amortized cost, Within one year	$ 20,956
Debt securities, Available-for-sale, Amortized cost, After one year through three years	147,047
Debt securities, Available-for-sale, Amortized cost, After three years through five years	73,238
Debt securities, Available-for-sale, Amortized cost, After five years through ten years	10,485
Debt securities, Available-for-sale, Amortized cost, After ten years	70,705
Debt securities, Available-for-sale, Amortized cost, Total	1,056,867
Debt securities, Available-for-sale, Estimated fair value, Within one year	21,529
Debt securities, Available-for-sale, Estimated fair value, After one year through three years	148,503
Debt securities, Available-for-sale, Estimated fair value, After three years through five years	72,788
Debt securities, Available-for-sale, Estimated fair value, After five years through ten years	11,204
Debt securities, Available-for-sale, Estimated fair value, After ten years	72,985
Debt securities, Available-for-sale, Estimated fair value, Total	1,074,114
Debt securities, Held-to-maturity, Amortized cost, Within one year	0
Debt securities, Held-to-maturity, Amortized cost, After one year through three years	0
Debt securities, Held-to-maturity, Amortized cost, After three years through five years	15,126
Debt securities, Held-to-maturity, Amortized cost, After five years through ten years	50,068
Debt securities, Held-to-maturity, Amortized cost, After ten years	38,542
Debt securities, Held-to-maturity, Amortized cost, Total	103,736
Debt securities, Held-to-maturity, Estimated fair value, Within one year	0
Debt securities, Held-to-maturity, Estimated fair value, After one year through three years	0
Debt securities, Held-to-maturity, Estimated fair value, After three years through five years	15,126
Debt securities, Held-to-maturity, Estimated fair value, After five years through ten years	50,068
Debt securities, Held-to-maturity, Estimated fair value, After ten years	37,438
Debt securities, Held-to-maturity, Estimated fair value, Total	102,632
Mortgage-backed securities [Member]
Debt securities, Available-for-sale, Amortized cost, After three years through five years	9,698
Debt securities, Available-for-sale, Amortized cost, After five years through ten years	75,658
Debt securities, Available-for-sale, Amortized cost, After ten years	649,080
Debt securities, Available-for-sale, Estimated fair value, After three years through five years	10,051
Debt securities, Available-for-sale, Estimated fair value, After five years through ten years	76,098
Debt securities, Available-for-sale, Estimated fair value, After ten years	660,956
Debt securities, Held-to-maturity, Amortized cost, After three years through five years	0
Debt securities, Held-to-maturity, Amortized cost, After five years through ten years	0
Debt securities, Held-to-maturity, Amortized cost, After ten years	0
Debt securities, Held-to-maturity, Estimated fair value, After three years through five years	0
Debt securities, Held-to-maturity, Estimated fair value, After five years through ten years	0
Debt securities, Held-to-maturity, Estimated fair value, After ten years	$ 0