Fair Value Measurements (Details 1) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Securities available‑for‑sale	$ 3,347,546	$ 3,559,437
Warrants Not Settleable in Cash, Fair Value Disclosure	5,192	4,914
Level 1
Securities available‑for‑sale		71,942
Level 2
Securities available‑for‑sale		3,388,054
Level 3
Securities available‑for‑sale		99,441
Government agency and government-sponsored enterprise pass through securities
Securities available‑for‑sale	520,519	667,840
Government agency and government-sponsored enterprise collateralized mortgage obligations
Securities available‑for‑sale	165,211	194,755
Municipal securities
Securities available‑for‑sale	1,553,286	1,547,331
Government agency and government-sponsored enterprise commercial mortgage-backed securities
Securities available‑for‑sale	464,399	391,441
US Treasury securities
Securities available‑for‑sale	0	69,380
SBA securities
Securities available‑for‑sale	197,301	211,157
Corporate debt securities
Securities available‑for‑sale	46,727	48,424
Collateralized loan obligations
Securities available‑for‑sale	153,887	132,189
US Government-sponsored Enterprises Debt Securities
Securities available‑for‑sale	0	36,913
Asset-backed and other securities
Securities available‑for‑sale	96,647	115,211
Fair Value, Measurements, Recurring
Securities available‑for‑sale	3,347,546
Derivative Asset, Fair Value of Collateral	2,484	11,919
Assets, Fair Value Disclosure, Recurring	3,355,222	3,576,270
Derivative Liability, Fair Value of Collateral	2,740	1,397
Fair Value, Measurements, Recurring | Level 1
Securities available‑for‑sale	2,714	71,942
Derivative Asset, Fair Value of Collateral	0	0
Warrants Not Settleable in Cash, Fair Value Disclosure	0	0
Assets, Fair Value Disclosure, Recurring	2,714	71,942
Derivative Liability, Fair Value of Collateral	0	0
Fair Value, Measurements, Recurring | Level 2
Securities available‑for‑sale	3,259,666	3,388,054
Derivative Asset, Fair Value of Collateral	2,484	11,919
Warrants Not Settleable in Cash, Fair Value Disclosure	0	0
Assets, Fair Value Disclosure, Recurring	3,262,150	3,399,973
Derivative Liability, Fair Value of Collateral	2,740	1,397
Fair Value, Measurements, Recurring | Level 3
Securities available‑for‑sale	85,166	99,441
Derivative Asset, Fair Value of Collateral	0	0
Warrants Not Settleable in Cash, Fair Value Disclosure	5,192	4,914
Assets, Fair Value Disclosure, Recurring	90,358	104,355
Derivative Liability, Fair Value of Collateral	0	0
Fair Value, Measurements, Recurring | Government agency and government-sponsored enterprise pass through securities | Level 1
Securities available‑for‑sale	0	0
Fair Value, Measurements, Recurring | Government agency and government-sponsored enterprise pass through securities | Level 2
Securities available‑for‑sale	520,519	667,840
Fair Value, Measurements, Recurring | Government agency and government-sponsored enterprise pass through securities | Level 3
Securities available‑for‑sale	0	0
Fair Value, Measurements, Recurring | Government agency and government-sponsored enterprise collateralized mortgage obligations | Level 1
Securities available‑for‑sale	0	0
Fair Value, Measurements, Recurring | Government agency and government-sponsored enterprise collateralized mortgage obligations | Level 2
Securities available‑for‑sale	165,211	194,755
Fair Value, Measurements, Recurring | Government agency and government-sponsored enterprise collateralized mortgage obligations | Level 3
Securities available‑for‑sale	0	0
Fair Value, Measurements, Recurring | Private Label Collateralized Mortgage Obligations | Level 1
Securities available‑for‑sale	0	0
Fair Value, Measurements, Recurring | Private Label Collateralized Mortgage Obligations | Level 2
Securities available‑for‑sale	80,539	63,555
Fair Value, Measurements, Recurring | Private Label Collateralized Mortgage Obligations | Level 3
Securities available‑for‑sale	69,030	81,241
Fair Value, Measurements, Recurring | Municipal securities | Level 1
Securities available‑for‑sale	0	0
Fair Value, Measurements, Recurring | Municipal securities | Level 2
Securities available‑for‑sale	1,553,286	1,547,331
Fair Value, Measurements, Recurring | Municipal securities | Level 3
Securities available‑for‑sale	0	0
Fair Value, Measurements, Recurring | Government agency and government-sponsored enterprise commercial mortgage-backed securities | Level 1
Securities available‑for‑sale	0	0
Fair Value, Measurements, Recurring | Government agency and government-sponsored enterprise commercial mortgage-backed securities | Level 2
Securities available‑for‑sale	464,399	391,441
Fair Value, Measurements, Recurring | Government agency and government-sponsored enterprise commercial mortgage-backed securities | Level 3
Securities available‑for‑sale	0	0
Fair Value, Measurements, Recurring | US Treasury securities | Level 1
Securities available‑for‑sale		69,380
Fair Value, Measurements, Recurring | US Treasury securities | Level 2
Securities available‑for‑sale		0
Fair Value, Measurements, Recurring | US Treasury securities | Level 3
Securities available‑for‑sale		0
Fair Value, Measurements, Recurring | SBA securities | Level 1
Securities available‑for‑sale	0	0
Fair Value, Measurements, Recurring | SBA securities | Level 2
Securities available‑for‑sale	197,301	211,157
Fair Value, Measurements, Recurring | SBA securities | Level 3
Securities available‑for‑sale	0	0
Fair Value, Measurements, Recurring | Corporate debt securities | Level 1
Securities available‑for‑sale	0	0
Fair Value, Measurements, Recurring | Corporate debt securities | Level 2
Securities available‑for‑sale	46,727	48,424
Fair Value, Measurements, Recurring | Corporate debt securities | Level 3
Securities available‑for‑sale	0	0
Fair Value, Measurements, Recurring | Collateralized loan obligations | Level 1
Securities available‑for‑sale	0	0
Fair Value, Measurements, Recurring | Collateralized loan obligations | Level 2
Securities available‑for‑sale	153,887	132,189
Fair Value, Measurements, Recurring | Collateralized loan obligations | Level 3
Securities available‑for‑sale	0	0
Fair Value, Measurements, Recurring | US Government-sponsored Enterprises Debt Securities | Level 1
Securities available‑for‑sale		0
Fair Value, Measurements, Recurring | US Government-sponsored Enterprises Debt Securities | Level 2
Securities available‑for‑sale		36,913
Fair Value, Measurements, Recurring | US Government-sponsored Enterprises Debt Securities | Level 3
Securities available‑for‑sale		0
Fair Value, Measurements, Recurring | Asset-backed and other securities | Level 1
Securities available‑for‑sale	2,714	2,562
Fair Value, Measurements, Recurring | Asset-backed and other securities | Level 2
Securities available‑for‑sale	77,797	94,449
Fair Value, Measurements, Recurring | Asset-backed and other securities | Level 3
Securities available‑for‑sale	$ 16,136	$ 18,200