Allowance for Loan and Lease Losses (Summary of Activity In Allowance for Loan and Lease Losses) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013		Dec. 31, 2012
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	$ 233,394	$ 319,018		$ 270,144
Reclassification	0	7,368	[1]	0
Provisions	640	(32,255)		142,885
Charge-offs	(37,770)	(68,026)		(100,478)
Recoveries	8,202	7,289		6,467
Net charge-offs	(29,568)	(60,737)		(94,011)
Ending balance	204,466	233,394		319,018
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Total allowance for loan and lease losses	204,466	233,394		319,018
Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases individually evaluated for impairment	119,593	132,146
Loans and leases collectively evaluated for impairment	17,463,374	11,972,152
Loans and leases, not acquired in a transfer accounted for as debt securities	17,582,967	12,104,298
Loan and Lease Acquired with Deteriorated Credit Quality [Abstract]
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Carrying Amount, Net	1,186,498	1,029,426		1,809,235
Commercial
Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases, not acquired in a transfer accounted for as debt securities	11,263,074	8,499,348
Loan and Lease Acquired with Deteriorated Credit Quality [Abstract]
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Carrying Amount, Net	726,123	781,307
Commercial | Construction and land development
Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases, not acquired in a transfer accounted for as debt securities	550,568	319,847
Loan and Lease Acquired with Deteriorated Credit Quality [Abstract]
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Carrying Amount, Net	78,079	78,915
Commercial | Mortgage
Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases, not acquired in a transfer accounted for as debt securities	7,552,948	6,362,490
Loan and Lease Acquired with Deteriorated Credit Quality [Abstract]
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Carrying Amount, Net	577,518	642,891
Commercial | Other commercial real estate
Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases, not acquired in a transfer accounted for as debt securities	244,875	178,754
Loan and Lease Acquired with Deteriorated Credit Quality [Abstract]
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Carrying Amount, Net	40,193	41,381
Commercial | Commercial and industrial
Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases, not acquired in a transfer accounted for as debt securities	1,988,934	1,081,158
Loan and Lease Acquired with Deteriorated Credit Quality [Abstract]
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Carrying Amount, Net	27,254	17,254
Commercial | Lease financing
Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases, not acquired in a transfer accounted for as debt securities	571,916	381,763
Commercial | Other
Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases, not acquired in a transfer accounted for as debt securities	353,833	175,336
Loan and Lease Acquired with Deteriorated Credit Quality [Abstract]
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Carrying Amount, Net	3,079	866
Commercial | Consumer and Other
Loan and Lease Acquired with Deteriorated Credit Quality [Abstract]
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Carrying Amount, Net	3,079	866
Noncommercial
Allowance for Loan and Lease Losses [Roll Forward]
Reclassification	7,368
Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases, not acquired in a transfer accounted for as debt securities	6,319,893	3,604,950
Loan and Lease Acquired with Deteriorated Credit Quality [Abstract]
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Carrying Amount, Net	460,375	248,119
Noncommercial | Mortgage
Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases, not acquired in a transfer accounted for as debt securities	2,520,542	982,421
Loan and Lease Acquired with Deteriorated Credit Quality [Abstract]
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Carrying Amount, Net	382,340	213,851
Noncommercial | Construction and land development
Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases, not acquired in a transfer accounted for as debt securities	120,097	122,792
Loan and Lease Acquired with Deteriorated Credit Quality [Abstract]
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Carrying Amount, Net	912	2,583
Noncommercial | Revolving mortgage
Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases, not acquired in a transfer accounted for as debt securities	2,561,800	2,113,285
Loan and Lease Acquired with Deteriorated Credit Quality [Abstract]
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Carrying Amount, Net	74,109	30,834
Noncommercial | Consumer
Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases, not acquired in a transfer accounted for as debt securities	1,117,454	386,452
Loan and Lease Acquired with Deteriorated Credit Quality [Abstract]
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Carrying Amount, Net	3,014	851
Noncommercial | Non-specific
Allowance for Loan and Lease Losses [Roll Forward]
Reclassification	(15,772)
Non-PCI Loans
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	179,874	179,046		180,883
Reclassification		7,368	[1]
Provisions	15,260	19,289		42,046
Charge-offs	(20,499)	(33,118)		(50,208)
Recoveries	8,202	7,289		6,325
Net charge-offs	(12,297)	(25,829)		(43,883)
Ending balance	182,837	179,874		179,046
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
ALLL for loans and leases individually evaluated for impairment	15,717	10,161
ALLL for loans and leases collectively evaluated for impairment	167,120	169,713
Total allowance for loan and lease losses	182,837	179,874		179,046
Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases individually evaluated for impairment	119,593	132,146
Loans and leases, not acquired in a transfer accounted for as debt securities	17,582,967	12,104,298
Non-PCI Loans | Commercial | Construction and land development
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	10,335	6,031		5,467
Reclassification		5,141	[1]
Provisions	1,735	2,809		9,665
Charge-offs	(316)	(4,685)		(9,546)
Recoveries	207	1,039		445
Ending balance	11,961	10,335		6,031
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
ALLL for loans and leases individually evaluated for impairment	92	103
ALLL for loans and leases collectively evaluated for impairment	11,869	10,232
Total allowance for loan and lease losses	11,961	10,335		6,031
Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases individually evaluated for impairment	1,620	2,272
Loans and leases collectively evaluated for impairment	548,948	317,575
Loans and leases, not acquired in a transfer accounted for as debt securities	550,568	319,847
Non-PCI Loans | Commercial | Mortgage
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	100,257	80,229		67,486
Reclassification		27,421	[1]
Provisions	(16,746)	(4,485)		18,198
Charge-offs	(1,147)	(3,904)		(7,081)
Recoveries	2,825	996		1,626
Ending balance	85,189	100,257		80,229
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
ALLL for loans and leases individually evaluated for impairment	8,610	6,873
ALLL for loans and leases collectively evaluated for impairment	76,579	93,384
Total allowance for loan and lease losses	85,189	100,257		80,229
Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases individually evaluated for impairment	82,803	97,111
Loans and leases collectively evaluated for impairment	7,470,145	6,265,379
Loans and leases, not acquired in a transfer accounted for as debt securities	7,552,948	6,362,490
Non-PCI Loans | Commercial | Other commercial real estate
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	1,009	2,059		2,169
Reclassification		(815)	[1]
Provisions	(401)	(32)		130
Charge-offs	0	(312)		(254)
Recoveries	124	109		14
Ending balance	732	1,009		2,059
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
ALLL for loans and leases individually evaluated for impairment	112	209
ALLL for loans and leases collectively evaluated for impairment	620	800
Total allowance for loan and lease losses	732	1,009		2,059
Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases individually evaluated for impairment	584	1,878
Loans and leases collectively evaluated for impairment	244,291	176,876
Loans and leases, not acquired in a transfer accounted for as debt securities	244,875	178,754
Non-PCI Loans | Commercial | Commercial and industrial
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	22,362	14,050		23,723
Reclassification		7,551	[1]
Provisions	10,441	4,333		(4,982)
Charge-offs	(3,014)	(4,785)		(5,472)
Recoveries	938	1,213		781
Ending balance	30,727	22,362		14,050
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
ALLL for loans and leases individually evaluated for impairment	1,743	771
ALLL for loans and leases collectively evaluated for impairment	28,984	21,591
Total allowance for loan and lease losses	30,727	22,362		14,050
Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases individually evaluated for impairment	11,040	9,300
Loans and leases collectively evaluated for impairment	1,977,894	1,071,858
Loans and leases, not acquired in a transfer accounted for as debt securities	1,988,934	1,081,158
Non-PCI Loans | Commercial | Lease financing
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	4,749	3,521		3,288
Reclassification		(253)	[1]
Provisions	(473)	1,646		498
Charge-offs	(100)	(272)		(361)
Recoveries	110	107		96
Ending balance	4,286	4,749		3,521
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
ALLL for loans and leases individually evaluated for impairment	150	54
ALLL for loans and leases collectively evaluated for impairment	4,136	4,695
Total allowance for loan and lease losses	4,286	4,749		3,521
Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases individually evaluated for impairment	623	188
Loans and leases collectively evaluated for impairment	571,293	381,575
Loans and leases, not acquired in a transfer accounted for as debt securities	571,916	381,763
Non-PCI Loans | Commercial | Other
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	190	1,175		1,315
Reclassification		(1,288)	[1]
Provisions	3,007	308		(116)
Charge-offs	(13)	(6)		(28)
Recoveries	0	1		4
Ending balance	3,184	190		1,175
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
ALLL for loans and leases individually evaluated for impairment	1,972	0
ALLL for loans and leases collectively evaluated for impairment	1,212	190
Total allowance for loan and lease losses	3,184	190		1,175
Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases individually evaluated for impairment	2,000	0
Loans and leases collectively evaluated for impairment	351,833	175,336
Loans and leases, not acquired in a transfer accounted for as debt securities	353,833	175,336
Non-PCI Loans | Noncommercial
Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases, not acquired in a transfer accounted for as debt securities	6,319,893	3,604,950
Non-PCI Loans | Noncommercial | Mortgage
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	10,511	3,836		8,879
Reclassification		5,717	[1]
Provisions	1,219	2,786		(782)
Charge-offs	(1,260)	(2,387)		(4,790)
Recoveries	191	559		529
Ending balance	10,661	10,511		3,836
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
ALLL for loans and leases individually evaluated for impairment	1,360	1,586
ALLL for loans and leases collectively evaluated for impairment	9,301	8,925
Total allowance for loan and lease losses	10,661	10,511		3,836
Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases individually evaluated for impairment	14,913	15,539
Loans and leases collectively evaluated for impairment	2,505,629	966,882
Loans and leases, not acquired in a transfer accounted for as debt securities	2,520,542	982,421
Non-PCI Loans | Noncommercial | Construction and land development
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	681	1,721		1,427
Reclassification		(478)	[1]
Provisions	245	(379)		1,161
Charge-offs	(118)	(392)		(1,047)
Recoveries	84	209		180
Ending balance	892	681		1,721
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
ALLL for loans and leases individually evaluated for impairment	71	72
ALLL for loans and leases collectively evaluated for impairment	821	609
Total allowance for loan and lease losses	892	681		1,721
Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases individually evaluated for impairment	1,340	1,108
Loans and leases collectively evaluated for impairment	118,757	121,684
Loans and leases, not acquired in a transfer accounted for as debt securities	120,097	122,792
Non-PCI Loans | Noncommercial | Revolving mortgage
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	16,239	25,185		27,045
Reclassification		(9,838)	[1]
Provisions	6,301	6,296		8,783
Charge-offs	(4,744)	(6,064)		(11,341)
Recoveries	854	660		698
Ending balance	18,650	16,239		25,185
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
ALLL for loans and leases individually evaluated for impairment	1,052	372
ALLL for loans and leases collectively evaluated for impairment	17,598	15,867
Total allowance for loan and lease losses	18,650	16,239		25,185
Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases individually evaluated for impairment	3,675	3,596
Loans and leases collectively evaluated for impairment	2,558,125	2,109,689
Loans and leases, not acquired in a transfer accounted for as debt securities	2,561,800	2,113,285
Non-PCI Loans | Noncommercial | Consumer
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	13,541	25,389		25,962
Reclassification		(10,018)	[1]
Provisions	9,932	6,085		7,763
Charge-offs	(9,787)	(10,311)		(10,288)
Recoveries	2,869	2,396		1,952
Ending balance	16,555	13,541		25,389
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
ALLL for loans and leases individually evaluated for impairment	555	121
ALLL for loans and leases collectively evaluated for impairment	16,000	13,420
Total allowance for loan and lease losses	16,555	13,541		25,389
Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases individually evaluated for impairment	995	1,154
Loans and leases collectively evaluated for impairment	1,116,459	385,298
Loans and leases, not acquired in a transfer accounted for as debt securities	1,117,454	386,452
Non-PCI Loans | Noncommercial | Non-specific
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	0	15,850		14,122
Reclassification		(15,772)	[1]
Provisions	0	(78)		1,728
Charge-offs	0	0		0
Recoveries	0	0		0
Ending balance	0	0		15,850
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Total allowance for loan and lease losses	0	0		15,850
Loans Acquired With Deteriorated Credit Quality [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	53,520	139,972		89,261
Reclassification		0	[1]
Provisions	(14,620)	(51,544)		100,839
Charge-offs	(17,271)	(34,908)		(50,270)
Recoveries	0	0		142
Net charge-offs	(17,271)	(34,908)		(50,128)
Ending balance	21,629	53,520		139,972
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Total allowance for loan and lease losses	21,629	53,520		139,972
Loan and Lease Acquired with Deteriorated Credit Quality [Abstract]
ALLL for loans and leases acquired with deteriorated credit quality	21,629	53,520
Loans and leases acquired with deteriorated credit quality		1,029,426
Loans Acquired With Deteriorated Credit Quality [Member] | Commercial | Construction and land development
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	1,320	31,186		16,693
Provisions	1,284	(22,942)		23,160
Charge-offs	(2,454)	(6,924)		(8,667)
Recoveries	0	0		0
Ending balance	150	1,320		31,186
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Total allowance for loan and lease losses	150	1,320		31,186
Loan and Lease Acquired with Deteriorated Credit Quality [Abstract]
ALLL for loans and leases acquired with deteriorated credit quality	150	1,320
Loans and leases acquired with deteriorated credit quality	78,079	78,915
Loans Acquired With Deteriorated Credit Quality [Member] | Commercial | Mortgage
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	29,906	50,275		39,557
Provisions	(7,903)	(3,872)		34,227
Charge-offs	(11,868)	(16,497)		(23,509)
Recoveries	0	0		0
Ending balance	10,135	29,906		50,275
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Total allowance for loan and lease losses	10,135	29,906		50,275
Loan and Lease Acquired with Deteriorated Credit Quality [Abstract]
ALLL for loans and leases acquired with deteriorated credit quality	10,135	29,906
Loans and leases acquired with deteriorated credit quality	577,518	642,891
Loans Acquired With Deteriorated Credit Quality [Member] | Commercial | Other commercial real estate
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	1,354	11,234		16,862
Provisions	(1,385)	(8,949)		(4,372)
Charge-offs	106	(931)		(1,256)
Recoveries	0	0
Ending balance	75	1,354		11,234
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Total allowance for loan and lease losses	75	1,354		11,234
Loan and Lease Acquired with Deteriorated Credit Quality [Abstract]
ALLL for loans and leases acquired with deteriorated credit quality	75	1,354
Loans and leases acquired with deteriorated credit quality	40,193	41,381
Loans Acquired With Deteriorated Credit Quality [Member] | Commercial | Commercial and industrial
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	5,275	8,897		5,500
Provisions	(2,023)	470		11,839
Charge-offs	(2,012)	(4,092)		(8,442)
Recoveries	0	0		0
Ending balance	1,240	5,275		8,897
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Total allowance for loan and lease losses	1,240	5,275		8,897
Loan and Lease Acquired with Deteriorated Credit Quality [Abstract]
ALLL for loans and leases acquired with deteriorated credit quality	1,240	5,275
Loans and leases acquired with deteriorated credit quality	27,254	17,254
Loans Acquired With Deteriorated Credit Quality [Member] | Commercial | Lease financing
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	0	0		13
Provisions	0	0		(13)
Charge-offs	0	0		0
Recoveries	0	0		0
Ending balance	0	0		0
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Total allowance for loan and lease losses	0	0		0
Loan and Lease Acquired with Deteriorated Credit Quality [Abstract]
ALLL for loans and leases acquired with deteriorated credit quality	0	0
Loans and leases acquired with deteriorated credit quality	0	0
Loans Acquired With Deteriorated Credit Quality [Member] | Noncommercial | Mortgage
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	11,802	19,837		5,433
Provisions	(5,576)	(5,487)		18,401
Charge-offs	(406)	(2,548)		(4,139)
Recoveries	0	0		142
Ending balance	5,820	11,802		19,837
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Total allowance for loan and lease losses	5,820	11,802		19,837
Loan and Lease Acquired with Deteriorated Credit Quality [Abstract]
ALLL for loans and leases acquired with deteriorated credit quality	5,820	11,802
Loans and leases acquired with deteriorated credit quality	382,339	213,851
Loans Acquired With Deteriorated Credit Quality [Member] | Noncommercial | Construction and land development
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	682	8,287		4,652
Provisions	(395)	(4,170)		6,520
Charge-offs	(104)	(3,435)		(2,885)
Recoveries	0	0		0
Ending balance	183	682		8,287
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Total allowance for loan and lease losses	183	682		8,287
Loan and Lease Acquired with Deteriorated Credit Quality [Abstract]
ALLL for loans and leases acquired with deteriorated credit quality	183	682
Loans and leases acquired with deteriorated credit quality	912	2,583
Loans Acquired With Deteriorated Credit Quality [Member] | Noncommercial | Revolving mortgage
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	2,959	9,754		77
Provisions	1,523	(6,399)		10,796
Charge-offs	(483)	(396)		(1,119)
Recoveries	0	0		0
Ending balance	3,999	2,959		9,754
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Total allowance for loan and lease losses	3,999	2,959		9,754
Loan and Lease Acquired with Deteriorated Credit Quality [Abstract]
ALLL for loans and leases acquired with deteriorated credit quality	3,999	2,959
Loans and leases acquired with deteriorated credit quality	74,109	30,834
Loans Acquired With Deteriorated Credit Quality [Member] | Noncommercial | Consumer and Other
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	222	502		474
Provisions	(145)	(195)		281
Charge-offs	(50)	(85)		(253)
Recoveries	0	0		0
Ending balance	27	222		502
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Total allowance for loan and lease losses	27	222		502
Loan and Lease Acquired with Deteriorated Credit Quality [Abstract]
ALLL for loans and leases acquired with deteriorated credit quality	27	222
Loans and leases acquired with deteriorated credit quality	$ 6,094	$ 1,717

[1] Reclassification results from enhancements to the ALLL calculation during the second quarter of 2013 that resulted in the allocation of $15.8 million previously designated as 'nonspecific' to other loan classes and the absorption of $7.4 million of the reserve for unfunded commitments related to unfunded, revocable loan commitments into the ALLL. Further discussion is contained in Note A.