Allowance for Loan and Lease Losses (Summary of Activity In Allowance for Loan and Lease Losses) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2012		Sep. 30, 2011		Sep. 30, 2012		Sep. 30, 2011		Dec. 31, 2011
Loans and Leases Evaluated for Impairment [Abstract]
Net loans and leases	$ 13,075,776	[1]	$ 13,906,792	[1]	$ 13,075,776	[1]	$ 13,906,792	[1]	$ 13,673,645	[2]
Loan and Lease Acquired with Deteriorated Credit Quality [Abstract]
Allowance for loan and lease losses	276,554	[1]	254,184	[1]	276,554	[1]	254,184	[1]	270,144	[2]
Noncovered Loans
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	185,132		180,615		180,883		176,517
Charge-offs	(7,680)		(17,059)		(39,105)		(41,159)
Recoveries	1,198		1,267		4,769		4,822
Provisions	7,397		14,311		39,500		38,954
Ending balance	186,047		179,134		186,047		179,134
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
ALLL for loans and leases individually evaluated for impairment	17,250		6,614		17,250		6,614		7,962
ALLL for loans and leases collectively evaluated for impairment	153,528		158,674		153,528		158,674		158,799
Non-specific ALLL	15,269		13,846		15,269		13,846		14,122
Total allowance for loan and lease losses	186,047		179,134		186,047		179,134
Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases individually evaluated for impairment	191,498		119,599		191,498		119,599		156,301
Loans and leases collectively evaluated for impairment	11,263,735		11,483,927		11,263,735		11,483,927		11,425,336
Net loans and leases	11,455,233		11,603,526		11,455,233		11,603,526		11,581,637
Covered Loans
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	87,797	[3]	69,435	[3]	89,261	[3]	51,248	[3]
Charge-offs	(7,516)	[3]	(25,255)	[3]	(37,403)	[3]	(80,983)	[3]
Recoveries	0	[3]	553	[3]	142	[3]	715	[3]
Provisions	10,226	[3]	30,317	[3]	38,507	[3]	104,070	[3]
Ending balance	90,507	[3]	75,050	[3]	90,507	[3]	75,050	[3]
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Total allowance for loan and lease losses	90,507	[3]	75,050	[3]	90,507	[3]	75,050	[3]
Loan and Lease Acquired with Deteriorated Credit Quality [Abstract]
ALLL for loans and leases acquired with deteriorated credit quality	90,507	[3]	75,050	[3]	90,507	[3]	75,050	[3]	89,261	[3]
Loans and leases acquired with deteriorated credit quality	1,897,097		2,557,450		1,897,097		2,557,450		2,362,152
Construction and Land Development - Commercial | Noncovered Loans
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	5,056		9,692		5,467		10,512
Charge-offs	(283)		(6,213)		(9,504)		(6,977)
Recoveries	101		74		370		153
Provisions	1,593		1,613		10,134		1,478
Ending balance	6,467		5,166		6,467		5,166
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
ALLL for loans and leases individually evaluated for impairment	2,977		310		2,977		310		1,139
ALLL for loans and leases collectively evaluated for impairment	3,490		4,856		3,490		4,856		4,328
Non-specific ALLL	0		0		0		0		0
Total allowance for loan and lease losses	6,467		5,166		6,467		5,166
Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases individually evaluated for impairment	24,175		22,001		24,175		22,001		26,782
Loans and leases collectively evaluated for impairment	295,568		394,718		295,568		394,718		354,381
Net loans and leases	319,743		416,719		319,743		416,719		381,163
Construction and Land Development - Commercial | Covered Loans
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	15,983	[3]	24,234	[3]	16,693	[3]	20,654	[3]
Charge-offs	(1,434)	[3]	(10,759)	[3]	(6,460)	[3]	(20,711)	[3]
Recoveries	0	[3]	57	[3]	0	[3]	57	[3]
Provisions	3,186	[3]	3,500	[3]	7,502	[3]	17,032	[3]
Ending balance	17,735	[3]	17,032	[3]	17,735	[3]	17,032	[3]
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Total allowance for loan and lease losses	17,735	[3]	17,032	[3]	17,735	[3]	17,032	[3]
Loan and Lease Acquired with Deteriorated Credit Quality [Abstract]
ALLL for loans and leases acquired with deteriorated credit quality	17,735	[3]	17,032	[3]	17,735	[3]	17,032	[3]	16,693	[3]
Loans and leases acquired with deteriorated credit quality	258,388		405,658		258,388		405,658		338,873
Commercial Mortgage | Noncovered Loans
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	70,966		67,123		67,486		64,772
Charge-offs	(1,428)		(1,184)		(5,448)		(3,810)
Recoveries	222		211		1,230		914
Provisions	347		1,807		6,839		6,081
Ending balance	70,107		67,957		70,107		67,957
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
ALLL for loans and leases individually evaluated for impairment	10,471		4,641		10,471		4,641		5,266
ALLL for loans and leases collectively evaluated for impairment	59,636		63,316		59,636		63,316		62,220
Non-specific ALLL	0		0		0		0		0
Total allowance for loan and lease losses	70,107		67,957		70,107		67,957
Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases individually evaluated for impairment	118,928		66,588		118,928		66,588		92,872
Loans and leases collectively evaluated for impairment	5,053,036		4,929,448		5,053,036		4,929,448		5,012,121
Net loans and leases	5,171,964		4,996,036		5,171,964		4,996,036		5,104,993
Commercial Mortgage | Covered Loans
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	35,991	[3]	22,093	[3]	39,557	[3]	13,199	[3]
Charge-offs	(3,006)	[3]	(8,728)	[3]	(18,398)	[3]	(32,735)	[3]
Recoveries	0	[3]	60	[3]	0	[3]	75	[3]
Provisions	8,159	[3]	16,607	[3]	19,985	[3]	49,493	[3]
Ending balance	41,144	[3]	30,032	[3]	41,144	[3]	30,032	[3]
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Total allowance for loan and lease losses	41,144	[3]	30,032	[3]	41,144	[3]	30,032	[3]
Loan and Lease Acquired with Deteriorated Credit Quality [Abstract]
ALLL for loans and leases acquired with deteriorated credit quality	41,144	[3]	30,032	[3]	41,144	[3]	30,032	[3]	39,557	[3]
Loans and leases acquired with deteriorated credit quality	1,109,048		1,310,083		1,109,048		1,310,083		1,260,589
Other Commercial Real Estate | Noncovered Loans
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	2,413		2,268		2,169		2,200
Charge-offs	0		0		(254)		0
Recoveries	6		6		6		17
Provisions	(180)		(113)		318		(56)
Ending balance	2,239		2,161		2,239		2,161
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
ALLL for loans and leases individually evaluated for impairment	292		43		292		43		283
ALLL for loans and leases collectively evaluated for impairment	1,947		2,118		1,947		2,118		1,886
Non-specific ALLL	0		0		0		0		0
Total allowance for loan and lease losses	2,239		2,161		2,239		2,161
Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases individually evaluated for impairment	3,309		580		3,309		580		5,686
Loans and leases collectively evaluated for impairment	155,458		143,958		155,458		143,958		139,085
Net loans and leases	158,767		144,538		158,767		144,538		144,771
Other Commercial Real Estate | Covered Loans
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	9,194	[3]	12,841	[3]	16,862	[3]	4,148	[3]
Charge-offs	(34)	[3]	(2,686)	[3]	(831)	[3]	(14,160)	[3]
Recoveries	0	[3]	386	[3]	0	[3]	477	[3]
Provisions	(4,606)	[3]	1,879	[3]	(11,477)	[3]	21,955	[3]
Ending balance	4,554	[3]	12,420	[3]	4,554	[3]	12,420	[3]
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Total allowance for loan and lease losses	4,554	[3]	12,420	[3]	4,554	[3]	12,420	[3]
Loan and Lease Acquired with Deteriorated Credit Quality [Abstract]
ALLL for loans and leases acquired with deteriorated credit quality	4,554	[3]	12,420	[3]	4,554	[3]	12,420	[3]	16,862	[3]
Loans and leases acquired with deteriorated credit quality	113,954		159,007		113,954		159,007		158,394
Commercial and Industrial | Noncovered Loans
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	24,915		24,918		23,723		24,089
Charge-offs	(720)		(1,010)		(3,766)		(4,659)
Recoveries	179		236		616		826
Provisions	591		(70)		4,392		3,818
Ending balance	24,965		24,074		24,965		24,074
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
ALLL for loans and leases individually evaluated for impairment	1,888		433		1,888		433		640
ALLL for loans and leases collectively evaluated for impairment	23,077		23,641		23,077		23,641		23,083
Non-specific ALLL	0		0		0		0		0
Total allowance for loan and lease losses	24,965		24,074		24,965		24,074
Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases individually evaluated for impairment	18,333		14,222		18,333		14,222		15,996
Loans and leases collectively evaluated for impairment	1,722,102		1,783,359		1,722,102		1,783,359		1,748,411
Net loans and leases	1,740,435		1,797,581		1,740,435		1,797,581		1,764,407
Commercial and Industrial | Covered Loans
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	14,724	[3]	1,872	[3]	5,500	[3]	6,828	[3]
Charge-offs	(1,901)	[3]	(624)	[3]	(7,916)	[3]	(3,067)	[3]
Recoveries	0	[3]	0	[3]	0	[3]	12	[3]
Provisions	(9,114)	[3]	5,687	[3]	6,125	[3]	3,162	[3]
Ending balance	3,709	[3]	6,935	[3]	3,709	[3]	6,935	[3]
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Total allowance for loan and lease losses	3,709	[3]	6,935	[3]	3,709	[3]	6,935	[3]
Loan and Lease Acquired with Deteriorated Credit Quality [Abstract]
ALLL for loans and leases acquired with deteriorated credit quality	3,709	[3]	6,935	[3]	3,709	[3]	6,935	[3]	5,500	[3]
Loans and leases acquired with deteriorated credit quality	59,787		137,253		59,787		137,253		113,442
Lease Financing | Noncovered Loans
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	3,515		3,358		3,288		3,384
Charge-offs	0		(77)		(335)		(341)
Recoveries	27		52		75		100
Provisions	(95)		(78)		419		112
Ending balance	3,447		3,255		3,447		3,255
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
ALLL for loans and leases individually evaluated for impairment	202		25		202		25		17
ALLL for loans and leases collectively evaluated for impairment	3,245		3,230		3,245		3,230		3,271
Non-specific ALLL	0		0		0		0		0
Total allowance for loan and lease losses	3,447		3,255		3,447		3,255
Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases individually evaluated for impairment	745		339		745		339		328
Loans and leases collectively evaluated for impairment	321,163		303,700		321,163		303,700		312,541
Net loans and leases	321,908		304,039		321,908		304,039		312,869
Lease Financing | Covered Loans
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	0	[3]	0	[3]	13	[3]	0	[3]
Charge-offs	0	[3]	0	[3]	0	[3]	0	[3]
Recoveries	0	[3]	0	[3]	0	[3]	0	[3]
Provisions	0	[3]	1	[3]	(13)	[3]	1	[3]
Ending balance	0	[3]	1	[3]	0	[3]	1	[3]
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Total allowance for loan and lease losses	0	[3]	1	[3]	0	[3]	1	[3]
Loan and Lease Acquired with Deteriorated Credit Quality [Abstract]
ALLL for loans and leases acquired with deteriorated credit quality	0	[3]	1	[3]	0	[3]	1	[3]	13	[3]
Loans and leases acquired with deteriorated credit quality	0		162		0		162		57
Other | Noncovered Loans
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	1,183		1,351		1,315		1,473
Charge-offs	0		(6)		(28)		(43)
Recoveries	0		1		4		2
Provisions	(7)		(63)		(115)		(149)
Ending balance	1,176		1,283		1,176		1,283
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
ALLL for loans and leases individually evaluated for impairment	59		0		59		0		14
ALLL for loans and leases collectively evaluated for impairment	1,117		1,283		1,117		1,283		1,301
Non-specific ALLL	0		0		0		0		0
Total allowance for loan and lease losses	1,176		1,283		1,176		1,283
Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases individually evaluated for impairment	730		0		730		0		193
Loans and leases collectively evaluated for impairment	131,025		158,782		131,025		158,782		158,176
Net loans and leases	131,755		158,782		131,755		158,782		158,369
Residential Mortgage | Noncovered Loans
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	7,639		7,404		8,879		7,009
Charge-offs	(1,090)		(1,624)		(3,381)		(4,026)
Recoveries	121		44		433		835
Provisions	516		3,186		1,255		5,192
Ending balance	7,186		9,010		7,186		9,010
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
ALLL for loans and leases individually evaluated for impairment	984		1,025		984		1,025		411
ALLL for loans and leases collectively evaluated for impairment	6,202		7,985		6,202		7,985		8,468
Non-specific ALLL	0		0		0		0		0
Total allowance for loan and lease losses	7,186		9,010		7,186		9,010
Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases individually evaluated for impairment	17,533		12,033		17,533		12,033		9,776
Loans and leases collectively evaluated for impairment	797,344		804,705		797,344		804,705		774,342
Net loans and leases	814,877		816,738		814,877		816,738		784,118
Residential Mortgage | Covered Loans
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	5,575	[3]	3,653	[3]	5,433	[3]	113	[3]
Charge-offs	(819)	[3]	(1,409)	[3]	(3,431)	[3]	(4,143)	[3]
Recoveries	0	[3]	50	[3]	142	[3]	94	[3]
Provisions	4,754	[3]	1,878	[3]	7,366	[3]	8,108	[3]
Ending balance	9,510	[3]	4,172	[3]	9,510	[3]	4,172	[3]
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Total allowance for loan and lease losses	9,510	[3]	4,172	[3]	9,510	[3]	4,172	[3]
Loan and Lease Acquired with Deteriorated Credit Quality [Abstract]
ALLL for loans and leases acquired with deteriorated credit quality	9,510	[3]	4,172	[3]	9,510	[3]	4,172	[3]	5,433	[3]
Loans and leases acquired with deteriorated credit quality	289,160		380,405		289,160		380,405		327,568
Revolving Mortgage | Noncovered Loans
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	26,700		22,020		27,045		18,016
Charge-offs	(1,613)		(3,686)		(7,885)		(10,454)
Recoveries	87		184		501		530
Provisions	1,213		7,099		6,726		17,525
Ending balance	26,387		25,617		26,387		25,617
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
ALLL for loans and leases individually evaluated for impairment	1		0		1		0		0
ALLL for loans and leases collectively evaluated for impairment	26,386		25,617		26,386		25,617		27,045
Non-specific ALLL	0		0		0		0		0
Total allowance for loan and lease losses	26,387		25,617		26,387		25,617
Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases individually evaluated for impairment	3,593		0		3,593		0		0
Loans and leases collectively evaluated for impairment	2,240,866		2,302,482		2,240,866		2,302,482		2,296,306
Net loans and leases	2,244,459		2,302,482		2,244,459		2,302,482		2,296,306
Revolving Mortgage | Covered Loans
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	2,548	[3]	10	[3]	77	[3]	676	[3]
Charge-offs	0	[3]	0	[3]	0	[3]	0	[3]
Recoveries	0	[3]	0	[3]	0	[3]	0	[3]
Provisions	2,946	[3]	122	[3]	5,417	[3]	(544)	[3]
Ending balance	5,494	[3]	132	[3]	5,494	[3]	132	[3]
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Total allowance for loan and lease losses	5,494	[3]	132	[3]	5,494	[3]	132	[3]
Loan and Lease Acquired with Deteriorated Credit Quality [Abstract]
ALLL for loans and leases acquired with deteriorated credit quality	5,494	[3]	132	[3]	5,494	[3]	132	[3]	77	[3]
Loans and leases acquired with deteriorated credit quality	37,280		39,709		37,280		39,709		51,552
Construction and Land Development - Non - Commercial | Noncovered Loans
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	1,815		1,324		1,427		1,751
Charge-offs	(239)		(358)		(914)		(1,432)
Recoveries	16		12		168		173
Provisions	530		448		1,441		934
Ending balance	2,122		1,426		2,122		1,426
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
ALLL for loans and leases individually evaluated for impairment	298		92		298		92		145
ALLL for loans and leases collectively evaluated for impairment	1,824		1,334		1,824		1,334		1,282
Non-specific ALLL	0		0		0		0		0
Total allowance for loan and lease losses	2,122		1,426		2,122		1,426
Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases individually evaluated for impairment	3,012		2,844		3,012		2,844		3,676
Loans and leases collectively evaluated for impairment	129,340		136,341		129,340		136,341		133,595
Net loans and leases	132,352		139,185		132,352		139,185		137,271
Construction and Land Development - Non - Commercial | Covered Loans
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	3,780	[3]	4,720	[3]	4,652	[3]	5,607	[3]
Charge-offs	(292)	[3]	(1,034)	[3]	(301)	[3]	(6,078)	[3]
Recoveries	0	[3]	0	[3]	0	[3]	0	[3]
Provisions	3,440	[3]	584	[3]	2,577	[3]	4,741	[3]
Ending balance	6,928	[3]	4,270	[3]	6,928	[3]	4,270	[3]
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Total allowance for loan and lease losses	6,928	[3]	4,270	[3]	6,928	[3]	4,270	[3]
Loan and Lease Acquired with Deteriorated Credit Quality [Abstract]
ALLL for loans and leases acquired with deteriorated credit quality	6,928	[3]	4,270	[3]	6,928	[3]	4,270	[3]	4,652	[3]
Loans and leases acquired with deteriorated credit quality	26,408		115,126		26,408		115,126		105,536
Consumer | Noncovered Loans
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	24,988		27,079		25,962		29,448
Charge-offs	(2,307)		(2,901)		(7,590)		(9,417)
Recoveries	439		447		1,366		1,272
Provisions	3,562		714		6,944		4,036
Ending balance	26,682		25,339		26,682		25,339
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
ALLL for loans and leases individually evaluated for impairment	78		45		78		45		47
ALLL for loans and leases collectively evaluated for impairment	26,604		25,294		26,604		25,294		25,915
Non-specific ALLL	0		0		0		0		0
Total allowance for loan and lease losses	26,682		25,339		26,682		25,339
Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases individually evaluated for impairment	1,140		992		1,140		992		992
Loans and leases collectively evaluated for impairment	417,833		526,434		417,833		526,434		496,378
Net loans and leases	418,973		527,426		418,973		527,426		497,370
Consumer | Covered Loans
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	2	[3]	12	[3]	474	[3]	23	[3]
Charge-offs	(30)	[3]	(15)	[3]	(66)	[3]	(89)	[3]
Recoveries	0	[3]		[3]	0	[3]	0	[3]
Provisions	1,461	[3]	59	[3]	1,025	[3]	122	[3]
Ending balance	1,433	[3]	56	[3]	1,433	[3]	56	[3]
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
Total allowance for loan and lease losses	1,433	[3]	56	[3]	1,433	[3]	56	[3]
Loan and Lease Acquired with Deteriorated Credit Quality [Abstract]
ALLL for loans and leases acquired with deteriorated credit quality	1,433	[3]	56	[3]	1,433	[3]	56	[3]	474	[3]
Loans and leases acquired with deteriorated credit quality	3,072		10,047		3,072		10,047		6,141
Non-Specific | Noncovered Loans
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	15,942		14,078		14,122		13,863
Charge-offs	0		0		0		0
Recoveries	0		0		0		0
Provisions	(673)		(232)		1,147		(17)
Ending balance	15,269		13,846		15,269		13,846
Allowance for Loans and Leases Evaluated for Impairment [Abstract]
ALLL for loans and leases individually evaluated for impairment	0		0		0		0		0
ALLL for loans and leases collectively evaluated for impairment	0		0		0		0		0
Non-specific ALLL	15,269		13,846		15,269		13,846		14,122
Total allowance for loan and lease losses	15,269		13,846		15,269		13,846
Loans and Leases Evaluated for Impairment [Abstract]
Loans and leases individually evaluated for impairment	0		0		0		0		0
Loans and leases collectively evaluated for impairment	0		0		0		0		0
Net loans and leases	0		0		0		0		0
Pooled Loans
Loan and Lease Acquired with Deteriorated Credit Quality [Abstract]
Allowance for loan and lease losses	$ 16,452		$ 0		$ 16,452		$ 0		$ 1,099

[1] Unaudited

[2] Derived from 2011 Annual Report on Form 10-K.

[3] The allowance of $16,452 at September 30, 2012, and $1,099 at December 31, 2011, relating to pooled loans is included in the loan classes above based on the primary loan class within each pool. No such allowance existed as of September 30, 2011.