Securities - Schedule of Unrealized Loss and Fair Value on Investments (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Fair Value
Less than 12 months	$ 301,140	$ 430,645
12 months or longer	226,642	80,825
Total	527,782	511,470
Unrealized Losses
Less than 12 months	(3,672)	(15,561)
12 months or longer	(6,354)	(4,442)
Total	(10,026)	(20,003)
Mortgage-backed Securities, US Government Sponsored Enterprises [Member]
Fair Value
Less than 12 months	100	33,425
12 months or longer	0	35,043
Total	100	68,468
Unrealized Losses
Less than 12 months	0	(2,045)
12 months or longer	0	(2,144)
Total	0	(4,189)
Collateralized Mortgage Obligations Of US Government Sponsored Entities [Member]
Fair Value
Less than 12 months	36,890	287,312
12 months or longer	21,640	45,657
Total	58,530	332,969
Unrealized Losses
Less than 12 months	(153)	(12,450)
12 months or longer	(271)	(2,297)
Total	(424)	(14,747)
Private mortage backed securities [Member]
Fair Value
Less than 12 months	100,148	29,574
12 months or longer	170,400	0
Total	270,548	29,574
Unrealized Losses
Less than 12 months	(833)	(226)
12 months or longer	(5,523)	0
Total	(6,356)	(226)
Private collaterlized mortgage obligations [Member]
Fair Value
Less than 12 months	61,554	47,653
12 months or longer	10,091	0
Total	71,600	47,653
Unrealized Losses
Less than 12 months	(914)	(413)
12 months or longer	(157)	0
Total	(1,071)	(413)
Collateralized Loan Obligations [Member]
Fair Value
Less than 12 months	100,714	32,179
12 months or longer	24,511	0
Total	125,200	32,179
Unrealized Losses
Less than 12 months	(1,769)	(413)
12 months or longer	(403)	0
Total	(2,172)	(413)
Obligations of state and political subdivisions [Member]
Fair Value
Less than 12 months	1,734	502
12 months or longer	0	125
Total	1,734	627
Unrealized Losses
Less than 12 months	(3)	(14)
12 months or longer	0	(1)
Total	$ (3)	$ (15)