Securities (Details 4) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Available-for-sale securities, Amortized cost
Due in one year or less	$ 21,957	$ 39,552	[1]
Due after one year through five years	229,402	355,296	[1]
Due after five years through ten years	381,530	255,795	[1]
Due after ten years	31,424	3,041	[1]
Total	1,432,434	1,347,358	[1]
Available-for-sale securities, Fair value
Due in one year or less	22,249	39,990
Due after one year through five years	239,169	370,933
Due after five years through ten years	375,541	264,966
Due after ten years	30,248	3,032
Total	1,432,472	1,391,297
Total debt securities
Available-for-sale securities, Amortized cost
Total	664,313	653,684	[1]
Available-for-sale securities, Fair value
Total	667,207	678,921
Mortgage-backed securities
Available-for-sale securities, Amortized cost
Total	768,121	693,674	[1]
Available-for-sale securities, Fair value
Total	$ 765,265	$ 712,376

[1] Net of other-than-temporary impairment losses recognized in earnings.