Available-For-Sale Securities (Contractual Maturities of Available-for-Sale Securities) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]
Due in one year or less, Amortized Cost	$ 188,594	$ 121,400
Due in one year or less, Fair Value	189,015	121,662
Due in one to five years, Amortized Cost	419,588	532,828
Due in one to five years, Fair Value	419,654	530,632
Due in five to ten years, Amortized Cost	361,037	95,279
Due in five to ten years, Fair Value	362,135	95,508
Due after ten years, Amortized Cost	501,177	261,315
Due after ten years, Fair Value	503,999	264,321
Total available-for-sale securities, Amortized Cost	1,785,113	1,284,733
Available-for-sale securities, at fair value	1,796,076	1,291,797
Mortgage-Backed [Member]
Schedule of Available-for-sale Securities [Line Items]
Total available-for-sale securities, Amortized Cost	261,871	236,316
Available-for-sale securities, at fair value	271,574	248,551
Other Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Total available-for-sale securities, Amortized Cost	52,846	37,595
Available-for-sale securities, at fair value	$ 49,699	$ 31,123