Loans (Summary of Recorded Investment of Consumer Loans by Risk Rating Categories) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment [Line Items]
Loans	$ 15,269,779	$ 14,155,267
Consumer Loan Portfolio
Financing Receivable, Recorded Investment [Line Items]
Loans	5,757,912	5,694,740
Consumer Loan Portfolio | Residential mortgage
Financing Receivable, Recorded Investment [Line Items]
Loans	3,458,666	3,252,487
Consumer Loan Portfolio | Consumer installment
Financing Receivable, Recorded Investment [Line Items]
Loans	1,521,074	1,613,008
Consumer Loan Portfolio | Home equity
Financing Receivable, Recorded Investment [Line Items]
Loans	778,172	829,245
Originated
Financing Receivable, Recorded Investment [Line Items]
Loans	11,844,756	9,747,429
Originated | Residential mortgage
Financing Receivable, Recorded Investment [Line Items]
Loans	2,407,305	1,967,857
Originated | Consumer installment
Financing Receivable, Recorded Investment [Line Items]
Loans	1,451,352	1,510,540
Originated | Home equity
Financing Receivable, Recorded Investment [Line Items]
Loans	612,129	611,846
Originated | Consumer Loan Portfolio
Financing Receivable, Recorded Investment [Line Items]
Loans	4,470,786	4,090,243
Originated | Consumer Loan Portfolio | Performing
Financing Receivable, Recorded Investment [Line Items]
Loans	4,457,918	4,076,461
Originated | Consumer Loan Portfolio | Nonperforming
Financing Receivable, Recorded Investment [Line Items]
Loans	12,868	13,782
Originated | Consumer Loan Portfolio | Residential mortgage
Financing Receivable, Recorded Investment [Line Items]
Loans	2,407,305	1,967,857
Originated | Consumer Loan Portfolio | Residential mortgage | Performing
Financing Receivable, Recorded Investment [Line Items]
Loans	2,399,317	1,959,222
Originated | Consumer Loan Portfolio | Residential mortgage | Nonperforming
Financing Receivable, Recorded Investment [Line Items]
Loans	7,988	8,635
Originated | Consumer Loan Portfolio | Consumer installment
Financing Receivable, Recorded Investment [Line Items]
Loans	1,451,352	1,510,540
Originated | Consumer Loan Portfolio | Consumer installment | Performing
Financing Receivable, Recorded Investment [Line Items]
Loans	1,450,076	1,509,698
Originated | Consumer Loan Portfolio | Consumer installment | Nonperforming
Financing Receivable, Recorded Investment [Line Items]
Loans	1,276	842
Originated | Consumer Loan Portfolio | Home equity
Financing Receivable, Recorded Investment [Line Items]
Loans	612,129	611,846
Originated | Consumer Loan Portfolio | Home equity | Performing
Financing Receivable, Recorded Investment [Line Items]
Loans	608,525	607,541
Originated | Consumer Loan Portfolio | Home equity | Nonperforming
Financing Receivable, Recorded Investment [Line Items]
Loans	3,604	4,305
Acquired
Financing Receivable, Recorded Investment [Line Items]
Loans	3,425,023	4,407,838
Acquired | Consumer Loan Portfolio
Financing Receivable, Recorded Investment [Line Items]
Loans	1,287,126	1,604,497
Acquired | Consumer Loan Portfolio | Residential mortgage
Financing Receivable, Recorded Investment [Line Items]
Loans	1,051,361	1,284,630
Acquired | Consumer Loan Portfolio | Consumer installment
Financing Receivable, Recorded Investment [Line Items]
Loans	69,722	102,468
Acquired | Consumer Loan Portfolio | Home equity
Financing Receivable, Recorded Investment [Line Items]
Loans	$ 166,043	$ 217,399