Fair Value Fair Value (Assets and liabilities measured at fair value on a nonrecurring basis) (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans Receivable, Fair Value Disclosure	$ 6,478,525	$ 6,441,458
Other Assets, Fair Value Disclosure	6,451,435	6,426,869
Other Repossessed Assets	4,100	4,200
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans Receivable, Fair Value Disclosure	24,936	12,499
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans Receivable, Fair Value Disclosure	6,453,589	6,428,959
Other Assets, Fair Value Disclosure	6,451,435	6,426,869
Fair Value, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans Receivable, Fair Value Disclosure	2,154	2,090
Servicing Asset at Fair Value, Amount	8,762	5,797
Other Assets, Fair Value Disclosure	2,977	3,033
Other Repossessed Assets	3,599	3,599
Fair Value, Nonrecurring [Member] | Residential Real Estate [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans Receivable, Fair Value Disclosure	164	217
Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Servicing Asset at Fair Value, Amount	8,762	5,797
Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans Receivable, Fair Value Disclosure	2,154	2,090
Other Assets, Fair Value Disclosure	2,977	3,033
Other Repossessed Assets	3,599	3,599
Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member] | Residential Real Estate [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans Receivable, Fair Value Disclosure	164	217
Commercial Real Estate Portfolio Segment [Member] | Fair Value, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans Receivable, Fair Value Disclosure	1,990	1,873
Commercial Real Estate Portfolio Segment [Member] | Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans Receivable, Fair Value Disclosure	1,990	1,873
Residential Real Estate [Member] | Fair Value, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Assets, Fair Value Disclosure	682	738
Residential Real Estate [Member] | Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Assets, Fair Value Disclosure	682	738
Commercial Real Estate [Member] | Fair Value, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Assets, Fair Value Disclosure	2,295	2,295
Commercial Real Estate [Member] | Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Assets, Fair Value Disclosure	2,295	2,295
Reported Value Measurement [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans Receivable, Fair Value Disclosure	6,461,016	6,444,725
Other Assets, Fair Value Disclosure	$ 6,433,926	$ 6,430,136