Loans (Balances Of Commercial Loan Portfolio Classes, Disaggregated By PD Grade) (Details) $ in Thousands	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($) grade	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans collectively evaluated for impairment	$ 27,344,254			$ 19,697,240
Total loans individually evaluated for impairment	234,651			265,330
Purchased credit-impaired loans	122,835			26,749
Allowance for Loan Losses	185,462	$ 187,194	$ 189,555	197,257	$ 201,968	$ 202,068
Allowance - collectively evaluated for impairment	149,751			153,742
Allowance - individually evaluated for impairment	32,704			42,985
Allowance - purchased credit-impaired loans	3,007		3,200	$ 530
Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans collectively evaluated for impairment	20,456,785		20,091,018
Total loans individually evaluated for impairment	34,851		45,431
Purchased credit-impaired loans	83,465		135,519
Total commercial loans	$ 20,575,101		$ 20,271,968
Percent of total commercial loans (percent)	100.00%		100.00%
Percent of loan collectively evaluated for impairment (percent)	99.00%		99.00%
Percent of loan individually evaluated for impairment (percent)	0.00%		0.00%
Percent of loan purchased-credit impaired (percent)	1.00%		1.00%
Allowance for Loan Losses	$ 130,666		$ 126,638
Allowance - collectively evaluated for impairment	127,173		117,649
Allowance - individually evaluated for impairment	1,213		6,176
Allowance - purchased credit-impaired loans	2,280		2,813
General C&I | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans collectively evaluated for impairment	13,691,127		13,511,033
Total loans individually evaluated for impairment	29,617		39,957
Purchased credit-impaired loans	56,335		99,407
Total commercial loans	13,777,079		13,650,397
Loans to Mortgage Companies | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans collectively evaluated for impairment	2,354,836		2,099,961
Total loans individually evaluated for impairment	0		0
Purchased credit-impaired loans	0		0
Total commercial loans	2,354,836		2,099,961
TRUPS
Accounts, Notes, Loans and Financing Receivable [Line Items]
Valuation allowance	25,500		25,500
TRUPS | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans collectively evaluated for impairment	303,848		303,848
Total loans individually evaluated for impairment	2,982		3,067
Purchased credit-impaired loans	0		0
Total commercial loans	306,830		306,915
Valuation allowance	25,500		$ 25,500
Highest internal grade | grade			13
Income CRE | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans collectively evaluated for impairment	4,011,198		$ 4,077,337
Total loans individually evaluated for impairment	1,748		1,612
Purchased credit-impaired loans	23,781		31,615
Total commercial loans	4,036,727		4,110,564
Residential CRE | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans collectively evaluated for impairment	95,776		98,839
Total loans individually evaluated for impairment	504		795
Purchased credit-impaired loans	3,349		4,497
Total commercial loans	99,629		104,131
Commercial Loan P D Grade One | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	$ 549,758		$ 538,744
Percent of total commercial loans (percent)	3.00%		3.00%
Allowance for Loan Losses	$ 64		$ 70
Commercial Loan P D Grade One | General C&I | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	547,654		536,244
Commercial Loan P D Grade One | Loans to Mortgage Companies | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	0		0
Commercial Loan P D Grade One | TRUPS | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	0		0
Commercial Loan P D Grade One | Income CRE | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	2,104		2,500
Commercial Loan P D Grade One | Residential CRE | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	0		0
Commercial Loan P D Grade Two | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	$ 850,399		$ 879,502
Percent of total commercial loans (percent)	4.00%		4.00%
Allowance for Loan Losses	$ 280		$ 339
Commercial Loan P D Grade Two | General C&I | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	840,122		877,635
Commercial Loan P D Grade Two | Loans to Mortgage Companies | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	0		0
Commercial Loan P D Grade Two | TRUPS | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	0		0
Commercial Loan P D Grade Two | Income CRE | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	10,236		1,798
Commercial Loan P D Grade Two | Residential CRE | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	41		69
Commercial Loan P D Grade Three | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	$ 1,615,382		$ 1,445,319
Percent of total commercial loans (percent)	8.00%		7.00%
Allowance for Loan Losses	$ 255		$ 272
Commercial Loan P D Grade Three | General C&I | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	633,000		582,224
Commercial Loan P D Grade Three | Loans to Mortgage Companies | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	727,078		652,982
Commercial Loan P D Grade Three | TRUPS | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	0		0
Commercial Loan P D Grade Three | Income CRE | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	255,090		210,073
Commercial Loan P D Grade Three | Residential CRE | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	214		40
Commercial Loan P D Grade Four | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	$ 1,889,436		$ 1,898,712
Percent of total commercial loans (percent)	9.00%		9.00%
Allowance for Loan Losses	$ 700		$ 854
Commercial Loan P D Grade Four | General C&I | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	845,405		959,581
Commercial Loan P D Grade Four | Loans to Mortgage Companies | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	586,315		629,432
Commercial Loan P D Grade Four | TRUPS | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	0		0
Commercial Loan P D Grade Four | Income CRE | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	457,716		309,699
Commercial Loan P D Grade Four | Residential CRE | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	0		0
Commercial Loan P D Grade Five | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	$ 2,768,352		$ 2,208,347
Percent of total commercial loans (percent)	13.00%		11.00%
Allowance for Loan Losses	$ 8,003		$ 7,355
Commercial Loan P D Grade Five | General C&I | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	1,892,574		1,461,632
Commercial Loan P D Grade Five | Loans to Mortgage Companies | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	347,919		328,477
Commercial Loan P D Grade Five | TRUPS | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	63,017		0
Commercial Loan P D Grade Five | Income CRE | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	463,421		415,764
Commercial Loan P D Grade Five | Residential CRE | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	1,421		2,474
Commercial Loan P D Grade Six | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	$ 2,446,870		$ 2,463,301
Percent of total commercial loans (percent)	12.00%		12.00%
Allowance for Loan Losses	$ 8,830		$ 10,495
Commercial Loan P D Grade Six | General C&I | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	1,475,963		1,668,247
Commercial Loan P D Grade Six | Loans to Mortgage Companies | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	426,654		335,169
Commercial Loan P D Grade Six | TRUPS | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	90,296		0
Commercial Loan P D Grade Six | Income CRE | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	447,840		456,706
Commercial Loan P D Grade Six | Residential CRE | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	6,117		3,179
Commercial Loan P D Grade Seven | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	$ 3,067,034		$ 2,869,430
Percent of total commercial loans (percent)	15.00%		14.00%
Allowance for Loan Losses	$ 14,442		$ 13,490
Commercial Loan P D Grade Seven | General C&I | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	2,387,509		2,257,400
Commercial Loan P D Grade Seven | Loans to Mortgage Companies | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	109,693		47,720
Commercial Loan P D Grade Seven | TRUPS | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	65,193		0
Commercial Loan P D Grade Seven | Income CRE | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	499,585		554,590
Commercial Loan P D Grade Seven | Residential CRE | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	5,054		9,720
Commercial Loan P D Grade Eight | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	$ 1,385,383		$ 1,376,652
Percent of total commercial loans (percent)	7.00%		7.00%
Allowance for Loan Losses	$ 19,828		$ 21,831
Commercial Loan P D Grade Eight | General C&I | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	1,078,583		1,092,994
Commercial Loan P D Grade Eight | Loans to Mortgage Companies | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	70,924		35,266
Commercial Loan P D Grade Eight | TRUPS | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	4,068		0
Commercial Loan P D Grade Eight | Income CRE | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	220,208		241,938
Commercial Loan P D Grade Eight | Residential CRE | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	11,600		6,454
Commercial Loan P D Grade Nine | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	$ 4,178,663		$ 4,396,420
Percent of total commercial loans (percent)	20.00%		22.00%
Allowance for Loan Losses	$ 22,349		$ 9,804
Commercial Loan P D Grade Nine | General C&I | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	2,604,602		2,633,854
Commercial Loan P D Grade Nine | Loans to Mortgage Companies | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	86,253		70,915
Commercial Loan P D Grade Nine | TRUPS | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	45,117		0
Commercial Loan P D Grade Nine | Income CRE | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	1,382,306		1,630,176
Commercial Loan P D Grade Nine | Residential CRE | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	60,385		61,475
Commercial Loan P D Grade Ten | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	$ 447,937		$ 421,424
Percent of total commercial loans (percent)	2.00%		2.00%
Allowance for Loan Losses	$ 8,782		$ 8,808
Commercial Loan P D Grade Ten | General C&I | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	371,017		373,537
Commercial Loan P D Grade Ten | Loans to Mortgage Companies | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	0		0
Commercial Loan P D Grade Ten | TRUPS | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	18,536		0
Commercial Loan P D Grade Ten | Income CRE | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	54,896		43,297
Commercial Loan P D Grade Ten | Residential CRE | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	3,488		4,590
Commercial Loan P D Grade Eleven | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	$ 298,673		$ 261,103
Percent of total commercial loans (percent)	1.00%		1.00%
Allowance for Loan Losses	$ 7,509		$ 6,784
Commercial Loan P D Grade Eleven | General C&I | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	257,439		226,382
Commercial Loan P D Grade Eleven | Loans to Mortgage Companies | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	0		0
Commercial Loan P D Grade Eleven | TRUPS | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	0		0
Commercial Loan P D Grade Eleven | Income CRE | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	40,893		31,785
Commercial Loan P D Grade Eleven | Residential CRE | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	341		2,936
Commercial Loan P D Grade Twelve | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	$ 416,972		$ 573,366
Percent of total commercial loans (percent)	2.00%		3.00%
Allowance for Loan Losses	$ 5,802		$ 5,882
Commercial Loan P D Grade Twelve | General C&I | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	300,482		409,838
Commercial Loan P D Grade Twelve | Loans to Mortgage Companies | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	0		0
Commercial Loan P D Grade Twelve | TRUPS | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	0		0
Commercial Loan P D Grade Twelve | Income CRE | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	110,184		156,717
Commercial Loan P D Grade Twelve | Residential CRE | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	6,306		6,811
Commercial Loan P D Grade Thirteen | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	$ 323,206		$ 522,436
Percent of total commercial loans (percent)	2.00%		3.00%
Allowance for Loan Losses	$ 8,895		$ 7,265
Commercial Loan P D Grade Thirteen | General C&I | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	247,731		202,613
Commercial Loan P D Grade Thirteen | Loans to Mortgage Companies | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	0		0
Commercial Loan P D Grade Thirteen | TRUPS | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	17,621		303,848
Commercial Loan P D Grade Thirteen | Income CRE | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	57,845		15,707
Commercial Loan P D Grade Thirteen | Residential CRE | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	9		268
Commercial Loan P D Grade Fourteen Fifteen Sixteen | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	$ 218,720		$ 236,262
Percent of total commercial loans (percent)	1.00%		1.00%
Allowance for Loan Losses	$ 21,434		$ 24,400
Commercial Loan P D Grade Fourteen Fifteen Sixteen | General C&I | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	209,046		228,852
Commercial Loan P D Grade Fourteen Fifteen Sixteen | Loans to Mortgage Companies | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	0		0
Commercial Loan P D Grade Fourteen Fifteen Sixteen | TRUPS | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	0		0
Commercial Loan P D Grade Fourteen Fifteen Sixteen | Income CRE | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	8,874		6,587
Commercial Loan P D Grade Fourteen Fifteen Sixteen | Residential CRE | Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial loan, Disaggregated by PD grade	$ 800		$ 823