Available-For-Sale Securities (Contractual Maturities Of Available-For-Sale Securities) (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2012
Schedule of Available-for-sale Securities [Line Items]
Due in one year or less, Amortized Cost	$ 284,334	$ 188,594	$ 67,163
Due in one to five years, Amortized Cost	320,175	419,588	467,468
Due in five to ten years, Amortized Cost	382,837	361,037	110,465
Due after ten years, Amortized Cost	528,490	501,177	256,675
Total available-for-sale securities, Amortized Cost	1,912,031	1,785,113	1,186,822
Due in one year or less, Fair Value	284,734	189,015	67,488
Due in one to five years, Fair Value	320,189	419,654	466,553
Due in five to ten years, Fair Value	366,341	362,135	109,780
Due after ten years, Fair Value	490,229	503,999	259,589
Available-for-sale securities, at fair value	1,843,824	1,796,076	1,196,702
Mortgage-Backed [Member]
Schedule of Available-for-sale Securities [Line Items]
Total available-for-sale securities, Amortized Cost	343,758	261,871	242,325
Available-for-sale securities, at fair value	332,767	271,574	255,742
Other Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Total available-for-sale securities, Amortized Cost	52,437	52,846	42,726
Available-for-sale securities, at fair value	$ 49,564	$ 49,699	$ 37,550