Allowance for Loan and Lease Losses (Allocation of Allowance for Loan and Lease Losses) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	$ 1,614,998	$ 2,025,905	$ 1,614,998	$ 2,025,905
Allowance for loan and lease losses	208,008		208,008		$ 206,216
Loans and Leases Receivable, Net Amount	20,534,563		20,534,563		20,033,774
PCI Loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Acquired loans which have adverse change in expected cash flows	394,600		394,600		469,300
Provision for Loan, Lease, and Other Losses	(2,146)	(1,275)	(4,143)	(4,139)
Financing Receivable, Allowance for Credit Losses, Write-downs	56	876	614	2,022
Recoveries	0	0	0	0
PCI Loans | Commercial | Construction and land development
Financing Receivable, Allowance for Credit Losses [Line Items]
Provision for Loan, Lease, and Other Losses	(453)	325	(802)	516
Financing Receivable, Allowance for Credit Losses, Write-downs	0	97	0	97
Recoveries	0	0	0	0
PCI Loans | Commercial | Mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Provision for Loan, Lease, and Other Losses	(935)	(2,065)	(1,914)	(2,990)
Financing Receivable, Allowance for Credit Losses, Write-downs	56	383	165	717
Recoveries	0	0	0	0
PCI Loans | Commercial | Other commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Provision for Loan, Lease, and Other Losses	(154)	(125)	(152)	(6)
Financing Receivable, Allowance for Credit Losses, Write-downs	0	0	5	0
Recoveries	0	0	0	0
PCI Loans | Commercial | Commercial and industrial
Financing Receivable, Allowance for Credit Losses [Line Items]
Provision for Loan, Lease, and Other Losses	60	399	(160)	(632)
Financing Receivable, Allowance for Credit Losses, Write-downs	0	87	0	285
Recoveries	0	0	0	0
PCI Loans | Noncommercial | Construction and land development
Financing Receivable, Allowance for Credit Losses [Line Items]
Provision for Loan, Lease, and Other Losses	0	(31)	0	(183)
Financing Receivable, Allowance for Credit Losses, Write-downs	0	0	0	0
Recoveries	0	0	0	0
PCI Loans | Noncommercial | Consumer and Other
Financing Receivable, Allowance for Credit Losses [Line Items]
Provision for Loan, Lease, and Other Losses	(105)	169	(101)	621
Financing Receivable, Allowance for Credit Losses, Write-downs	0	6	73	462
Recoveries	0	0	0	0
PCI Loans | Noncommercial | Mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Provision for Loan, Lease, and Other Losses	(382)	1,165	(729)	302
Financing Receivable, Allowance for Credit Losses, Write-downs	0	195	371	280
Recoveries	0	0	0	0
PCI Loans | Noncommercial | Revolving mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Provision for Loan, Lease, and Other Losses	(177)	(1,112)	(285)	(1,767)
Financing Receivable, Allowance for Credit Losses, Write-downs	0	108	0	181
Recoveries	0	0	0	0
Non-PCI Loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Total impaired noncovered loans and leases	130,393		130,393		150,367
Unpaid principal balance	140,804		140,804		167,966
Impaired Financing Receivable, Related Allowance	9,259		9,259		7,200
ALLL for loans and leases individually evaluated for impairment	9,259		9,259		7,200
Impaired Financing Receivable, with Related Allowance, Recorded Investment	69,135		69,135		66,861
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	61,258		61,258		83,506
Financing Receivable, Individually Evaluated for Impairment	130,393		130,393		150,367
Average balance	128,759	129,943	137,601	123,745
Interest income recognized	1,015	1,224	2,240	2,310
Provision for Loan, Lease, and Other Losses	6,708	8,994	13,548	17,650
Financing Receivable, Allowance for Credit Losses, Write-downs	5,841	6,050	12,061	12,080
Recoveries	2,560	1,971	5,062	4,442
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	187,194		187,194		182,704
Financing Receivable, Collectively Evaluated for Impairment	19,690,711		19,690,711		19,139,107
Loans and Leases Receivable, Net Amount	19,821,104		19,821,104		19,289,474
Non-PCI Loans | Commercial | Construction and land development
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	3,800		3,800		4,428
ALLL for loans and leases individually evaluated for impairment	333		333		123
Impaired Financing Receivable, with Related Allowance, Recorded Investment	2,164		2,164		1,623
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	1,135		1,135		1,471
Financing Receivable, Individually Evaluated for Impairment	3,299		3,299		3,094
Average balance	3,236	3,134	3,200	3,093
Interest income recognized	40	35	81	70
Provision for Loan, Lease, and Other Losses	291	88	1,234	1,191
Financing Receivable, Allowance for Credit Losses, Write-downs	136	221	562	239
Recoveries	129	104	209	166
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	16,836		16,836		16,165
Financing Receivable, Collectively Evaluated for Impairment	621,507		621,507		617,258
Loans and Leases Receivable, Net Amount	624,806		624,806		620,352
Non-PCI Loans | Commercial | Mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	84,095		84,095		103,763
ALLL for loans and leases individually evaluated for impairment	4,248		4,248		3,370
Impaired Financing Receivable, with Related Allowance, Recorded Investment	37,960		37,960		41,793
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	39,660		39,660		53,314
Financing Receivable, Individually Evaluated for Impairment	77,620		77,620		95,107
Average balance	79,442	86,253	86,193	83,115
Interest income recognized	616	840	1,382	1,602
Provision for Loan, Lease, and Other Losses	701	(1,878)	1,096	(5,557)
Financing Receivable, Allowance for Credit Losses, Write-downs	44	47	134	280
Recoveries	500	323	755	1,084
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	67,365		67,365		66,526
Financing Receivable, Collectively Evaluated for Impairment	8,427,639		8,427,639		8,179,441
Loans and Leases Receivable, Net Amount	8,505,259		8,505,259		8,274,548
Non-PCI Loans | Commercial | Other commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	1,875		1,875		863
ALLL for loans and leases individually evaluated for impairment	119		119		289
Impaired Financing Receivable, with Related Allowance, Recorded Investment	578		578		305
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	973		973		122
Financing Receivable, Individually Evaluated for Impairment	1,551		1,551		427
Average balance	878	403	651	477
Interest income recognized	7	0	12	1
Provision for Loan, Lease, and Other Losses	(79)	(227)	(184)	231
Financing Receivable, Allowance for Credit Losses, Write-downs	0	9	0	178
Recoveries	10	9	154	19
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	2,019		2,019		1,879
Financing Receivable, Collectively Evaluated for Impairment	336,067		336,067		320,594
Loans and Leases Receivable, Net Amount	337,618		337,618		321,021
Non-PCI Loans | Commercial | Commercial and industrial
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	10,670		10,670		21,455
ALLL for loans and leases individually evaluated for impairment	971		971		1,118
Impaired Financing Receivable, with Related Allowance, Recorded Investment	6,529		6,529		8,544
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	3,691		3,691		9,366
Financing Receivable, Individually Evaluated for Impairment	10,220		10,220		17,910
Average balance	9,938	14,088	12,744	12,220
Interest income recognized	84	146	235	249
Provision for Loan, Lease, and Other Losses	81	4,547	2,282	12,093
Financing Receivable, Allowance for Credit Losses, Write-downs	1,177	2,318	2,494	4,031
Recoveries	525	209	1,004	603
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	42,937		42,937		41,998
Financing Receivable, Collectively Evaluated for Impairment	2,375,939		2,375,939		2,351,048
Loans and Leases Receivable, Net Amount	2,386,159		2,386,159		2,368,958
Non-PCI Loans | Commercial | Lease financing
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	1,233		1,233		1,956
ALLL for loans and leases individually evaluated for impairment	45		45		213
Impaired Financing Receivable, with Related Allowance, Recorded Investment	1,209		1,209		1,651
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	24		24		104
Financing Receivable, Individually Evaluated for Impairment	1,233		1,233		1,755
Average balance	1,214	1,463	1,436	1,527
Interest income recognized	15	16	35	34
Provision for Loan, Lease, and Other Losses	343	408	62	419
Financing Receivable, Allowance for Credit Losses, Write-downs	0	6	0	21
Recoveries	1	11	180	22
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	5,721		5,721		5,311
Financing Receivable, Collectively Evaluated for Impairment	783,628		783,628		729,023
Loans and Leases Receivable, Net Amount	784,861		784,861		730,778
Non-PCI Loans | Commercial | Other
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	783		783		1,260
ALLL for loans and leases individually evaluated for impairment	0		0		0
Impaired Financing Receivable, with Related Allowance, Recorded Investment	0		0		0
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	695		695		1,183
Financing Receivable, Individually Evaluated for Impairment	695		695		1,183
Average balance	813	1,835	943	1,913
Interest income recognized	10	0	24	0
Provision for Loan, Lease, and Other Losses	37	(1,824)	(290)	(2,042)
Financing Receivable, Allowance for Credit Losses, Write-downs	88	0	160	0
Recoveries	29	31	350	46
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	1,755		1,755		1,855
Financing Receivable, Collectively Evaluated for Impairment	364,574		364,574		313,649
Loans and Leases Receivable, Net Amount	365,269		365,269		314,832
Non-PCI Loans | Noncommercial | Construction and land development
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	411		411		784
ALLL for loans and leases individually evaluated for impairment	0		0		49
Impaired Financing Receivable, with Related Allowance, Recorded Investment	0		0		693
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	411		411		91
Financing Receivable, Individually Evaluated for Impairment	411		411		784
Average balance	413	779	485	719
Interest income recognized	5	9	11	16
Provision for Loan, Lease, and Other Losses	78	74	165	192
Financing Receivable, Allowance for Credit Losses, Write-downs	0	0	0	22
Recoveries	0	3	3	71
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	1,653		1,653		1,436
Financing Receivable, Collectively Evaluated for Impairment	225,911		225,911		219,289
Loans and Leases Receivable, Net Amount	226,322		226,322		220,073
Non-PCI Loans | Noncommercial | Mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	27,772		27,772		25,043
ALLL for loans and leases individually evaluated for impairment	1,992		1,992		1,212
Impaired Financing Receivable, with Related Allowance, Recorded Investment	14,734		14,734		10,097
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	12,046		12,046		12,889
Financing Receivable, Individually Evaluated for Impairment	26,780		26,780		22,986
Average balance	24,982	16,819	24,240	16,092
Interest income recognized	178	135	350	260
Provision for Loan, Lease, and Other Losses	1,487	1,162	2,262	1,975
Financing Receivable, Allowance for Credit Losses, Write-downs	179	90	352	374
Recoveries	41	305	61	443
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	14,084		14,084		12,893
Financing Receivable, Collectively Evaluated for Impairment	2,751,083		2,751,083		2,672,999
Loans and Leases Receivable, Net Amount	2,777,863		2,777,863		2,695,985
Non-PCI Loans | Noncommercial | Revolving mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	8,607		8,607		7,120
ALLL for loans and leases individually evaluated for impairment	868		868		299
Impaired Financing Receivable, with Related Allowance, Recorded Investment	4,654		4,654		1,105
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	2,459		2,459		4,778
Financing Receivable, Individually Evaluated for Impairment	7,113		7,113		5,883
Average balance	6,421	4,015	6,365	3,501
Interest income recognized	40	23	72	39
Provision for Loan, Lease, and Other Losses	1,470	31	2,628	(431)
Financing Receivable, Allowance for Credit Losses, Write-downs	1,081	616	2,116	1,409
Recoveries	214	346	245	480
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	15,860		15,860		15,672
Financing Receivable, Collectively Evaluated for Impairment	2,526,415		2,526,415		2,517,223
Loans and Leases Receivable, Net Amount	2,533,528		2,533,528		2,523,106
Non-PCI Loans | Noncommercial | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	1,558		1,558		1,294
ALLL for loans and leases individually evaluated for impairment	683		683		527
Impaired Financing Receivable, with Related Allowance, Recorded Investment	1,307		1,307		1,050
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	164		164		188
Financing Receivable, Individually Evaluated for Impairment	1,471		1,471		1,238
Average balance	1,422	1,154	1,344	1,088
Interest income recognized	20	20	38	39
Provision for Loan, Lease, and Other Losses	2,299	6,613	4,293	9,579
Financing Receivable, Allowance for Credit Losses, Write-downs	3,136	2,743	6,243	5,526
Recoveries	1,111	$ 630	2,101	$ 1,508
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	18,964		18,964		18,969
Financing Receivable, Collectively Evaluated for Impairment	1,277,948		1,277,948		1,218,583
Loans and Leases Receivable, Net Amount	$ 1,279,419		$ 1,279,419		$ 1,219,821