Investment Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	$ 3,213,655	$ 3,512,385
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	32,386	62,157
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(22,211)	(15,105)
Securities available‑for‑sale	3,223,830	3,559,437
Government agency and government-sponsored enterprise pass through securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	499,185	660,069
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	6,222	11,517
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(2,964)	(3,746)
Government agency and government-sponsored enterprise collateralized mortgage obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	145,258	193,148
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	1,528	2,633
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(497)	(1,026)
Private Label Collateralized Mortgage Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	122,707	140,065
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	4,199	5,837
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(1,437)	(1,106)
Municipal Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	1,447,064	1,508,968
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	15,406	39,435
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(6,011)	(1,072)
Commercial Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	555,552	392,729
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	1,798	1,509
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(9,658)	(2,797)
Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	47,100	49,047
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	680	327
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(271)	(950)
Collateralized Loan Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	155,440	133,192
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	1,685	128
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(238)	(1,131)
Asset-backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	179,085	211,946
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	510	41
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(750)	(830)
US Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	0	70,196
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	0	0
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	0	(816)
Securities available‑for‑sale	0	69,380
US Government-sponsored Enterprises Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	0	36,302
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	0	611
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	0	0
Securities available‑for‑sale	0	36,913
Other securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	62,264	116,723
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	358	119
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	$ (385)	$ (1,631)

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 25
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=51813488&loc=d3e22054-111558

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (aa)
-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27232-111563

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=49167202&loc=d3e26610-111562

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section S99
-Paragraph 1
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