Investment Securities (Maturities of Debt Securities) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013
Investment Securities Available-for-Sale:
Due in one year or less, Amortized Cost	$ 101,422
Due after one year through five years, Amortized Cost	109,213
Due after five years through ten years, Amortized Cost	446,924
Due after ten years, Amortized Cost	76,495
Preferred stock, Amortized Cost	1,389
Total Available-for-sale Securities, Debt Maturities, Amortized Cost	735,443
Due in one year or less , Fair Value	101,999
Due after one year through five years, Fair Value	110,633
Due after five years through ten years, Fair Value	443,441
Due after ten years, Fair Value	76,197
Preferred stock, Fair Value	1,782
Total Available-for-sale securities, Debt maturities, Fair Value	734,052
Investment Securities Held-to-Maturity:
Due in one year or less, Amortized Cost	46,155
Due after one year through five years, Amortized Cost	118,260
Due after five years through ten years, Amortized Cost	74,190
Due after ten years, Amortized Cost	36,110
Total Held-to-maturity securities, Debt maturities, Amortized Cost	274,715
Due in one year or less , Fair Value	46,148
Due after one year through five years, Fair Value	119,256
Due after five years through ten years, Fair Value	75,179
Due after ten years, Fair Value	30,814
Total Held-to-maturity securities, Debt maturities, Fair Value	$ 271,397