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, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	$ 2,025,905	$ 1,888,475	$ 2,025,905	$ 1,888,475
Allowance for loan and lease losses	208,317		208,317		$ 204,466
Loans and Leases Receivable, Net Amount	19,311,868		19,311,868		18,564,999
PCI Loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Acquired loans which have adverse change in expected cash flows	570,600		570,600		285,600
Provision for Loan, Lease, and Other Losses	(1,275)	(9,529)	(4,139)	(11,802)
Financing Receivable, Allowance for Credit Losses, Write-downs	876	6,133	2,022	12,387
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	325	(77)	516	3,278
Financing Receivable, Allowance for Credit Losses, Write-downs	97	596	97	795
Recoveries	0	0	0	0
PCI Loans | Commercial | Mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Provision for Loan, Lease, and Other Losses	(2,065)	(1,185)	(2,990)	(4,571)
Financing Receivable, Allowance for Credit Losses, Write-downs	383	4,503	717	8,020
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	(125)	(797)	(6)	(947)
Financing Receivable, Allowance for Credit Losses, Write-downs	0	0	0	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	399	(1,729)	(632)	(2,065)
Financing Receivable, Allowance for Credit Losses, Write-downs	87	152	285	2,835
Recoveries	0	0	0	0
PCI Loans | Noncommerical | Construction and land development
Financing Receivable, Allowance for Credit Losses [Line Items]
Provision for Loan, Lease, and Other Losses	(31)	(583)	(183)	(682)
Financing Receivable, Allowance for Credit Losses, Write-downs	0	0	0	0
Recoveries	0	0	0	0
PCI Loans | Noncommerical | Consumer and Other
Financing Receivable, Allowance for Credit Losses [Line Items]
Provision for Loan, Lease, and Other Losses	169	49	621	58
Financing Receivable, Allowance for Credit Losses, Write-downs	6	6	462	23
Recoveries	0	0	0	0
PCI Loans | Noncommerical | Mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Provision for Loan, Lease, and Other Losses	1,165	(2,176)	302	(4,476)
Financing Receivable, Allowance for Credit Losses, Write-downs	195	495	280	233
Recoveries	0	0	0	0
PCI Loans | Noncommerical | Revolving mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Provision for Loan, Lease, and Other Losses	(1,112)	(3,031)	(1,767)	(2,397)
Financing Receivable, Allowance for Credit Losses, Write-downs	108	381	181	481
Recoveries	0	0	0	0
Non-PCI Loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Total impaired noncovered loans and leases	125,006		125,006		119,593
Unpaid principal balance	142,184		142,184		133,466
Impaired Financing Receivable, Related Allowance	12,592		12,592		15,717
ALLL for loans and leases individually evaluated for impairment	12,592		12,592		15,717
Impaired Financing Receivable, with Related Allowance, Recorded Investment	79,737		79,737		87,007
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	45,269		45,269		32,586
Financing Receivable, Individually Evaluated for Impairment	125,006		125,006		119,593
Average balance	129,943	126,318	123,745	129,039
Interest income recognized	1,224	1,131	2,310	2,643
Provision for Loan, Lease, and Other Losses	8,994	2,230	17,650	2,600
Financing Receivable, Allowance for Credit Losses, Write-downs	6,050	4,771	12,080	9,193
Recoveries	1,971	1,507	4,442	3,634
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	180,257		180,257		167,120
Financing Receivable, Collectively Evaluated for Impairment	18,271,940		18,271,940		17,463,374
Loans and Leases Receivable, Net Amount	18,396,946		18,396,946		17,582,967
Non-PCI Loans | Commercial | Construction and land development
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	8,514		8,514		6,945
ALLL for loans and leases individually evaluated for impairment	445		445		92
Impaired Financing Receivable, with Related Allowance, Recorded Investment	2,620		2,620		996
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	472		472		624
Financing Receivable, Individually Evaluated for Impairment	3,092		3,092		1,620
Average balance	3,134	2,592	3,093	1,413
Interest income recognized	35	28	70	31
Provision for Loan, Lease, and Other Losses	88	(1,135)	1,191	750
Financing Receivable, Allowance for Credit Losses, Write-downs	221	0	239	0
Recoveries	104	5	166	31
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	12,634		12,634		11,869
Financing Receivable, Collectively Evaluated for Impairment	544,059		544,059		491,513
Loans and Leases Receivable, Net Amount	547,151		547,151		493,133
Non-PCI Loans | Commercial | Mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	89,251		89,251		87,702
ALLL for loans and leases individually evaluated for impairment	7,744		7,744		8,610
Impaired Financing Receivable, with Related Allowance, Recorded Investment	53,733		53,733		57,324
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	29,822		29,822		25,479
Financing Receivable, Individually Evaluated for Impairment	83,555		83,555		82,803
Average balance	86,253	87,687	83,115	84,359
Interest income recognized	840	799	1,602	1,716
Provision for Loan, Lease, and Other Losses	(1,878)	(1,961)	(5,557)	(8,940)
Financing Receivable, Allowance for Credit Losses, Write-downs	47	272	280	440
Recoveries	323	145	1,084	1,252
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	72,692		72,692		76,579
Financing Receivable, Collectively Evaluated for Impairment	7,778,035		7,778,035		7,470,145
Loans and Leases Receivable, Net Amount	7,861,590		7,861,590		7,552,948
Non-PCI Loans | Commercial | Other commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	848		848		913
ALLL for loans and leases individually evaluated for impairment	101		101		112
Impaired Financing Receivable, with Related Allowance, Recorded Investment	101		101		112
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	300		300		472
Financing Receivable, Individually Evaluated for Impairment	401		401		584
Average balance	403	1,981	477	2,731
Interest income recognized	0	7	1	60
Provision for Loan, Lease, and Other Losses	(227)	(155)	231	(229)
Financing Receivable, Allowance for Credit Losses, Write-downs	9	0	178	0
Recoveries	9	16	19	26
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	703		703		620
Financing Receivable, Collectively Evaluated for Impairment	287,813		287,813		244,291
Loans and Leases Receivable, Net Amount	288,214		288,214		244,875
Non-PCI Loans | Commercial | Commercial and industrial
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	15,816		15,816		12,197
ALLL for loans and leases individually evaluated for impairment	1,771		1,771		1,743
Impaired Financing Receivable, with Related Allowance, Recorded Investment	9,162		9,162		10,319
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	3,254		3,254		721
Financing Receivable, Individually Evaluated for Impairment	12,416		12,416		11,040
Average balance	14,088	11,208	12,220	15,690
Interest income recognized	146	113	249	353
Provision for Loan, Lease, and Other Losses	4,547	3,033	12,093	5,009
Financing Receivable, Allowance for Credit Losses, Write-downs	2,318	531	4,031	1,027
Recoveries	209	386	603	565
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	37,621		37,621		28,984
Financing Receivable, Collectively Evaluated for Impairment	2,187,175		2,187,175		1,977,894
Loans and Leases Receivable, Net Amount	2,199,591		2,199,591		1,988,934
Non-PCI Loans | Commercial | Lease financing
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	1,448		1,448		623
ALLL for loans and leases individually evaluated for impairment	146		146		150
Impaired Financing Receivable, with Related Allowance, Recorded Investment	1,177		1,177		319
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	271		271		304
Financing Receivable, Individually Evaluated for Impairment	1,448		1,448		623
Average balance	1,463	384	1,527	732
Interest income recognized	16	4	34	21
Provision for Loan, Lease, and Other Losses	408	176	419	(348)
Financing Receivable, Allowance for Credit Losses, Write-downs	6	14	21	72
Recoveries	11	20	22	36
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	4,560		4,560		4,136
Financing Receivable, Collectively Evaluated for Impairment	642,060		642,060		571,293
Loans and Leases Receivable, Net Amount	643,508		643,508		571,916
Non-PCI Loans | Commercial | Other
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	1,732		1,732		2,000
ALLL for loans and leases individually evaluated for impairment	17		17		1,972
Impaired Financing Receivable, with Related Allowance, Recorded Investment	1,732		1,732		2,000
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	0		0		0
Financing Receivable, Individually Evaluated for Impairment	1,732		1,732		2,000
Average balance	1,835	48	1,913	24
Interest income recognized	0	1	0	1
Provision for Loan, Lease, and Other Losses	(1,824)	163	(2,042)	435
Financing Receivable, Allowance for Credit Losses, Write-downs	0	5	0	13
Recoveries	31	0	46	0
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	1,171		1,171		1,212
Financing Receivable, Collectively Evaluated for Impairment	336,657		336,657		351,833
Loans and Leases Receivable, Net Amount	338,389		338,389		353,833
Non-PCI Loans | Noncommerical | Construction and land development
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	860		860		1,340
ALLL for loans and leases individually evaluated for impairment	0		0		71
Impaired Financing Receivable, with Related Allowance, Recorded Investment	0		0		1,077
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	860		860		263
Financing Receivable, Individually Evaluated for Impairment	860		860		1,340
Average balance	779	2,061	719	1,946
Interest income recognized	9	26	16	50
Provision for Loan, Lease, and Other Losses	74	(323)	192	254
Financing Receivable, Allowance for Credit Losses, Write-downs	0	23	22	94
Recoveries	3	2	71	64
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	1,133		1,133		821
Financing Receivable, Collectively Evaluated for Impairment	226,420		226,420		203,676
Loans and Leases Receivable, Net Amount	227,280		227,280		205,016
Non-PCI Loans | Noncommerical | Mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	17,118		17,118		15,746
ALLL for loans and leases individually evaluated for impairment	1,623		1,623		1,360
Impaired Financing Receivable, with Related Allowance, Recorded Investment	8,760		8,760		10,198
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	7,664		7,664		4,715
Financing Receivable, Individually Evaluated for Impairment	16,424		16,424		14,913
Average balance	16,819	15,592	16,092	15,824
Interest income recognized	135	107	260	284
Provision for Loan, Lease, and Other Losses	1,162	(1,557)	1,975	(948)
Financing Receivable, Allowance for Credit Losses, Write-downs	90	234	374	418
Recoveries	305	148	443	156
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	11,082		11,082		9,301
Financing Receivable, Collectively Evaluated for Impairment	2,580,640		2,580,640		2,478,145
Loans and Leases Receivable, Net Amount	2,597,064		2,597,064		2,493,058
Non-PCI Loans | Noncommerical | Revolving mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	5,403		5,403		4,933
ALLL for loans and leases individually evaluated for impairment	168		168		1,052
Impaired Financing Receivable, with Related Allowance, Recorded Investment	1,458		1,458		3,675
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	2,503		2,503		0
Financing Receivable, Individually Evaluated for Impairment	3,961		3,961		3,675
Average balance	4,015	3,779	3,501	4,262
Interest income recognized	23	29	39	76
Provision for Loan, Lease, and Other Losses	31	1,252	(431)	2,605
Financing Receivable, Allowance for Credit Losses, Write-downs	616	1,064	1,409	2,324
Recoveries	346	201	480	277
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	17,122		17,122		17,598
Financing Receivable, Collectively Evaluated for Impairment	2,525,975		2,525,975		2,558,125
Loans and Leases Receivable, Net Amount	2,529,936		2,529,936		2,561,800
Non-PCI Loans | Noncommerical | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	1,194		1,194		1,067
ALLL for loans and leases individually evaluated for impairment	577		577		555
Impaired Financing Receivable, with Related Allowance, Recorded Investment	994		994		987
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	123		123		8
Financing Receivable, Individually Evaluated for Impairment	1,117		1,117		995
Average balance	1,154	986	1,088	2,058
Interest income recognized	20	17	39	51
Provision for Loan, Lease, and Other Losses	6,613	2,737	9,579	4,012
Financing Receivable, Allowance for Credit Losses, Write-downs	2,743	2,628	5,526	4,805
Recoveries	630	$ 584	1,508	$ 1,227
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	21,539		21,539		16,000
Financing Receivable, Collectively Evaluated for Impairment	1,163,106		1,163,106		1,116,459
Loans and Leases Receivable, Net Amount	$ 1,164,223		$ 1,164,223		$ 1,117,454