Loans and Leases (Details 7) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Allowance for Loan and Lease Losses [Roll Forward]
Loans and Leases Receivable, Allowance, beginning balance	$ 157,238
Loans and Leases Receivable, Allowance, ending balance	139,456	$ 157,238
Loans held for investment, net	16,972,743	15,455,954
Non Purchased Credit Impaired Loans and Leases [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Loans and Leases Receivable, Allowance, beginning balance	143,755	105,534
Allowance for Loan and Lease Losses, Write-offs	(74,142)	(35,092)
Allowance for Loan and Lease Loss, Recovery of Bad Debts	11,185	13,102
Provision for Loan and Lease Losses	52,214	60,211
Loans and Leases Receivable, Allowance, ending balance	133,012	143,755
Financing Receivable, Individually Evaluated for Impairment	13,621	24,933
Financing Receivable, Collectively Evaluated for Impairment	119,391	118,822
Financing Receivable, Individually Evaluated for Impairment	210,735	234,430
Financing Receivable, Collectively Evaluated for Impairment	16,703,972	15,113,100
Loans held for investment, net	16,914,707	15,347,530
Purchased Credit Impaired Loans and Leases [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Loans and Leases Receivable, Allowance, beginning balance	13,483
Loans and Leases Receivable, Allowance, Covered, beginning balance	13,483	9,577
Allowance for Loan and Lease Losses, Write-offs	(6,154)	(862)
Allowance for Loan and Lease Loss, Recovery of Bad Debts	363	39
Provision for Loan and Lease Losses	(1,248)	4,729
Loans and Leases Receivable, Allowance, ending balance	6,444	13,483
Loans and Leases Receivable, Allowance, Covered, ending balance	6,444	13,483
Receivables Acquired With Deteriorated Credit Quality, Allowance For Credit Losses	6,444	13,483
Receivables Acquired with Deteriorated Credit Quality	58,036	108,424
Loans held for investment, net	58,036	108,424
NonPCI and PCI Loans [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Loans and Leases Receivable Allowance Covered And Noncovered, beginning balance	157,238	115,111
Allowance for Loan and Lease Losses, Write-offs	(80,296)	(35,954)
Allowance for Loan and Lease Loss, Recovery of Bad Debts	11,548	13,141
Provision for Loan and Lease Losses	50,966	64,940
Loans and Leases Receivable Allowance Covered And Noncovered, ending balance	139,456	157,238
Loans and Leases Receivable Net Of Deferred Income Covered And Noncovered	16,972,743	15,455,954
Mortgages [Member] | Non Purchased Credit Impaired Loans and Leases [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Loans and Leases Receivable, Allowance, beginning balance	37,765	36,654
Allowance for Loan and Lease Losses, Write-offs	(2,410)	(2,059)
Allowance for Loan and Lease Loss, Recovery of Bad Debts	1,209	4,519
Provision for Loan and Lease Losses	(1,583)	(1,349)
Loans and Leases Receivable, Allowance, ending balance	34,981	37,765
Financing Receivable, Individually Evaluated for Impairment	970	6,851
Financing Receivable, Collectively Evaluated for Impairment	34,011	30,914
Financing Receivable, Individually Evaluated for Impairment	115,319	123,348
Financing Receivable, Collectively Evaluated for Impairment	7,683,672	5,494,608
Loans held for investment, net	7,798,991	5,617,956
Real Estate Construction [Member] | Non Purchased Credit Impaired Loans and Leases [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Loans and Leases Receivable, Allowance, beginning balance	10,045	7,137
Allowance for Loan and Lease Losses, Write-offs	0	0
Allowance for Loan and Lease Loss, Recovery of Bad Debts	429	673
Provision for Loan and Lease Losses	2,581	2,235
Loans and Leases Receivable, Allowance, ending balance	13,055	10,045
Financing Receivable, Individually Evaluated for Impairment	0	0
Financing Receivable, Collectively Evaluated for Impairment	13,055	10,045
Financing Receivable, Individually Evaluated for Impairment	5,690	7,257
Financing Receivable, Collectively Evaluated for Impairment	1,585,539	955,582
Loans held for investment, net	1,591,229	962,839
Commercial Portfolio Segment [Member] | Non Purchased Credit Impaired Loans and Leases [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Loans and Leases Receivable, Allowance, beginning balance	93,853	61,082
Allowance for Loan and Lease Losses, Write-offs	(70,709)	(32,210)
Allowance for Loan and Lease Loss, Recovery of Bad Debts	9,415	7,794
Provision for Loan and Lease Losses	50,167	57,187
Loans and Leases Receivable, Allowance, ending balance	82,726	93,853
Financing Receivable, Individually Evaluated for Impairment	12,635	17,912
Financing Receivable, Collectively Evaluated for Impairment	70,091	75,941
Financing Receivable, Individually Evaluated for Impairment	89,626	103,431
Financing Receivable, Collectively Evaluated for Impairment	7,025,294	8,288,129
Loans held for investment, net	7,114,920	8,391,560
Consumer Portfolio Segment [Member] | Non Purchased Credit Impaired Loans and Leases [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Loans and Leases Receivable, Allowance, beginning balance	2,092	661
Allowance for Loan and Lease Losses, Write-offs	(1,023)	(823)
Allowance for Loan and Lease Loss, Recovery of Bad Debts	132	116
Provision for Loan and Lease Losses	1,049	2,138
Loans and Leases Receivable, Allowance, ending balance	2,250	2,092
Financing Receivable, Individually Evaluated for Impairment	16	170
Financing Receivable, Collectively Evaluated for Impairment	2,234	1,922
Financing Receivable, Individually Evaluated for Impairment	100	394
Financing Receivable, Collectively Evaluated for Impairment	409,467	374,781
Loans held for investment, net	$ 409,567	$ 375,175