Non-Covered Loans and Allowance for Non-Covered Loan Losses - Allowance (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2016	Dec. 31, 2015
Changes in the allowance for loan losses
Balance, beginning of period				$ 45,415					$ 45,415
Provision charged to (recapture from) operations operations	$ 4,347	$ 3,990	$ 28,876	3,407	$ 4,277	$ 5,593	$ 158	$ 2,687	40,620	$ 12,715	$ 16,933
Balance, end of period	54,186				45,415				54,186	45,415
Loan portfolio distributed by portfolio segment and impairment methodology
Total loans												$ 5,843,499	$ 5,207,617
Allowance for loan losses distributed by portfolio segment and impairment methodology
Total loans, allowance	54,186			45,415	45,415				$ 45,415	45,415		54,186	45,415
Originated Financing Receivable
Allowance for loan losses
Rolling period considered for average net loss rate to calculate historical loss factors									3 years
Weighted average loss rate for recent four quarters (as a percent)									120.00%
Weighted average loss rate for oldest four quarters (as a percent)									80.00%
Originated Financing Receivable | Minimum
Loan portfolio distributed by portfolio segment and impairment methodology
Loans individually evaluated for impairment												500
Noncovered
Changes in the allowance for loan losses
Balance, beginning of period				45,415				37,041	$ 45,415	37,041	33,241
Provision charged to (recapture from) operations operations									41,741	12,173	7,747
Loans charged off									(35,419)	(8,127)	(7,399)
Recoveries on charged off loans									2,449	4,328	3,452
Balance, end of period	54,186				45,415				54,186	45,415	37,041
Loan portfolio distributed by portfolio segment and impairment methodology
Loans individually evaluated for impairment												15,144	11,451
Loans collectively evaluated for impairment												5,776,923	5,124,112
Total loans												5,843,499	5,207,617
Allowance for loan losses distributed by portfolio segment and impairment methodology
Loans individually evaluated for impairment, allowance												282	1,380
Loans collectively evaluated for impairment, allowance												50,807	39,549
Total loans, allowance	54,186			45,415	45,415			37,041	45,415	37,041	33,241	54,186	45,415
Noncovered | Commercial and industrial
Changes in the allowance for loan losses
Balance, beginning of period				19,845				18,833	19,845	18,833	16,717
Provision charged to (recapture from) operations operations									33,369	4,598	6,099
Loans charged off									(33,776)	(7,144)	(6,926)
Recoveries on charged off loans									1,931	3,558	2,943
Balance, end of period	21,369				19,845				21,369	19,845	18,833
Loan portfolio distributed by portfolio segment and impairment methodology
Loans individually evaluated for impairment												4,508	11,354
Loans collectively evaluated for impairment												1,683,273	1,528,101
Total loans												1,696,453	1,552,805
Allowance for loan losses distributed by portfolio segment and impairment methodology
Loans individually evaluated for impairment, allowance												115	1,380
Loans collectively evaluated for impairment, allowance												20,697	17,124
Total loans, allowance	21,369			19,845	19,845			18,833	19,845	18,833	16,717	21,369	19,845
Noncovered | Real estate
Changes in the allowance for loan losses
Balance, beginning of period				18,983				11,131	18,983	11,131	8,331
Provision charged to (recapture from) operations operations									7,297	7,937	2,696
Loans charged off									(1,439)	(605)	(114)
Recoveries on charged off loans									395	520	218
Balance, end of period	25,236				18,983				25,236	18,983	11,131
Loan portfolio distributed by portfolio segment and impairment methodology
Loans individually evaluated for impairment												9,704	97
Loans collectively evaluated for impairment												2,768,064	2,260,367
Total loans												2,816,767	2,313,239
Allowance for loan losses distributed by portfolio segment and impairment methodology
Loans collectively evaluated for impairment, allowance												23,129	16,052
Total loans, allowance	25,236			18,983	18,983			11,131	18,983	11,131	8,331	25,236	18,983
Noncovered | Construction and land development
Changes in the allowance for loan losses
Balance, beginning of period				6,064				6,450	6,064	6,450	7,957
Provision charged to (recapture from) operations operations									938	(386)	(1,692)
Recoveries on charged off loans											185
Balance, end of period	7,002				6,064				7,002	6,064	6,450
Loan portfolio distributed by portfolio segment and impairment methodology
Loans individually evaluated for impairment												727
Loans collectively evaluated for impairment												782,656	700,206
Total loans												786,850	705,356
Allowance for loan losses distributed by portfolio segment and impairment methodology
Loans individually evaluated for impairment, allowance												167
Loans collectively evaluated for impairment, allowance												6,458	5,882
Total loans, allowance	7,002			6,064	6,064			6,450	6,064	6,450	7,957	7,002	6,064
Noncovered | Consumer
Changes in the allowance for loan losses
Balance, beginning of period				314				461	314	461	88
Provision charged to (recapture from) operations operations									190	104	627
Loans charged off									(203)	(378)	(359)
Recoveries on charged off loans									123	127	105
Balance, end of period	424				314				424	314	461
Loan portfolio distributed by portfolio segment and impairment methodology
Loans individually evaluated for impairment												205
Loans collectively evaluated for impairment												40,853	44,893
Total loans												41,352	45,672
Allowance for loan losses distributed by portfolio segment and impairment methodology
Loans collectively evaluated for impairment, allowance												368	282
Total loans, allowance	424			314	314			461	314	461	88	424	314
Noncovered | Broker-dealer
Changes in the allowance for loan losses
Balance, beginning of period				209				166	209	166	148
Provision charged to (recapture from) operations operations									(53)	(80)	17
Loans charged off									(1)
Recoveries on charged off loans										123	1
Balance, end of period	155				209				155	209	166
Loan portfolio distributed by portfolio segment and impairment methodology
Loans collectively evaluated for impairment												502,077	590,545
Total loans												502,077	590,545
Allowance for loan losses distributed by portfolio segment and impairment methodology
Loans collectively evaluated for impairment, allowance												155	209
Total loans, allowance	155			209	209			$ 166	209	166	$ 148	155	209
Noncovered | PCI loans
Changes in the allowance for loan losses
Balance, beginning of period				4,486					4,486
Balance, end of period	3,097				4,486				3,097	4,486
Loan portfolio distributed by portfolio segment and impairment methodology
Total loans												51,432	72,054
Allowance for loan losses distributed by portfolio segment and impairment methodology
Total loans, allowance	3,097			4,486	4,486				4,486	4,486		3,097	4,486
Noncovered | PCI loans | Commercial and industrial
Changes in the allowance for loan losses
Balance, beginning of period				1,341					1,341
Balance, end of period	557				1,341				557	1,341
Loan portfolio distributed by portfolio segment and impairment methodology
Total loans												8,672	13,350
Allowance for loan losses distributed by portfolio segment and impairment methodology
Total loans, allowance	557			1,341	1,341				1,341	1,341		557	1,341
Noncovered | PCI loans | Real estate
Changes in the allowance for loan losses
Balance, beginning of period				2,931					2,931
Balance, end of period	2,107				2,931				2,107	2,931
Loan portfolio distributed by portfolio segment and impairment methodology
Total loans												38,999	52,775
Allowance for loan losses distributed by portfolio segment and impairment methodology
Total loans, allowance	2,107			2,931	2,931				2,931	2,931		2,107	2,931
Noncovered | PCI loans | Construction and land development
Changes in the allowance for loan losses
Balance, beginning of period				182					182
Balance, end of period	377				182				377	182
Loan portfolio distributed by portfolio segment and impairment methodology
Total loans												3,467	5,150
Allowance for loan losses distributed by portfolio segment and impairment methodology
Total loans, allowance	377			182	182				182	182		377	182
Noncovered | PCI loans | Consumer
Changes in the allowance for loan losses
Balance, beginning of period				32					32
Balance, end of period	56				32				56	32
Loan portfolio distributed by portfolio segment and impairment methodology
Total loans												294	779
Allowance for loan losses distributed by portfolio segment and impairment methodology
Total loans, allowance	$ 56			$ 32	$ 32				$ 32	$ 32		$ 56	$ 32