Securities (Details) - Remaining Contractual Maturity of Securities (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Available-for-sale Securities, Amortized Cost Basis [Abstract]
One year or less	$ 65,157
After one year to five years	80,964
After five years to ten years	196,380
After ten years	130,648
Securities that do not have a single contractual maturity	544,792
Total	1,017,941	1,147,114
Available-for-sale Securities, Fair Value [Abstract]
One year or less	63,042
After one year to five years	78,335
After five years to ten years	190,004
After ten years	126,406
Securities that do not have a single contractual maturity	539,633
Total securities available-for-sale	997,420	1,112,725
Held-to-maturity Securities, Amortized Cost [Abstract]
One year or less	3,425
After one year to five years	8,505
After five years to ten years	5,703
After ten years	9,143
Securities that do not have a single contractual maturity	0
Total	26,776	44,322
Held-to-maturity Securities, Fair Value [Abstract]
One year or less	3,552
After one year to five years	8,819
After five years to ten years	5,914
After ten years	9,481
Securities that do not have a single contractual maturity	0
Total	$ 27,766	$ 43,387