Securities - Schedule of Unrealized Loss and Fair Value on Investments (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Fair Value
Less than 12 months	$ 664,476	$ 443,830
12 months or longer	198,397	254,229
Total	862,873	698,059
Unrealized Losses
Less than 12 months	(13,451)	(6,030)
12 months or longer	(4,992)	(6,673)
Total	(18,443)	(12,703)
Collateralized Loan Obligations [Member]
Fair Value
Less than 12 months	8,152	101,601
12 months or longer	51,694	60,922
Total	59,846	162,523
Unrealized Losses
Less than 12 months	(41)	(1,642)
12 months or longer	(938)	(1,612)
Total	(979)	(3,254)
Mortgage-backed Securities, US Government Sponsored Enterprises [Member]
Fair Value
Less than 12 months	327,759	112,236
12 months or longer	5,387	14,508
Total	333,146	126,744
Unrealized Losses
Less than 12 months	(5,991)	(1,082)
12 months or longer	(75)	(256)
Total	(6,066)	(1,338)
Collateralized Mortgage Obligations Of US Government Sponsored Entities [Member]
Fair Value
Less than 12 months	234,175	97,512
12 months or longer	58,912	147,266
Total	293,087	244,778
Unrealized Losses
Less than 12 months	(5,599)	(973)
12 months or longer	(2,096)	(4,333)
Total	(7,695)	(5,306)
Private mortage backed securities [Member]
Fair Value
Less than 12 months	0	31,792
12 months or longer	36,848	0
Total	36,848	31,792
Unrealized Losses
Less than 12 months	0	(766)
12 months or longer	(900)	0
Total	(900)	(766)
Private collaterlized mortgage obligations [Member]
Fair Value
Less than 12 months	1,460	19,939
12 months or longer	38,417	31,533
Total	39,877	51,472
Unrealized Losses
Less than 12 months	0	(321)
12 months or longer	(816)	(472)
Total	(816)	(793)
Obligations of state and political subdivisions [Member]
Fair Value
Less than 12 months	39,321	11,570
12 months or longer	0	0
Total	39,321	11,570
Unrealized Losses
Less than 12 months	(895)	(110)
12 months or longer	0	0
Total	(895)	(110)
Corporate and other debt securities [member]
Fair Value
Less than 12 months	33,008	31,342
12 months or longer	0	0
Total	33,008	31,342
Unrealized Losses
Less than 12 months	(517)	(416)
12 months or longer	0	0
Total	(517)	(416)
Private commercial mortgage backed securities [Member]
Fair Value
Less than 12 months	12,667	37,838
12 months or longer	7,139	0
Total	19,806	37,838
Unrealized Losses
Less than 12 months	(306)	(720)
12 months or longer	(167)	0
Total	(473)	$ (720)
Commercial mortgage backed securities of U.S. Government Sponsored Entities [Member]
Fair Value
Less than 12 months	7,934
12 months or longer	0
Total	7,934
Unrealized Losses
Less than 12 months	(102)
12 months or longer	0
Total	$ (102)