Summary of Significant Accounting Policies Narrative (Details)	12 Months Ended
	Dec. 31, 2016 USD ($) subsidiarytrusts	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Property, Plant and Equipment [Line Items]
Number of banks owned | subsidiarytrusts	6
Days past due for nonaccrual status	90 days
Period for which change in loans are evaluated individually for impairment quarterly	12 months
Individual impairment, outstanding commitment threshold	$ 1,000,000.0
Financing Receivable, Obtaining Certified Thrid-party Appraisal For Impaired Loans, Period	12 months
Collective impairment review, outstanding commitment threshold (less than $1.0 million)	$ 1,000,000.0
Impaired loans with principal balances	62.00%	69.00%
Impaired loans balances, real estate as collateral	$ 1,000,000
Threshold of companies current loan to value ratio of original appraisals used	70.00%
Foreign currency open position	$ 500,000
Award vesting period	3 years
Goodwill, impairment	$ 0	$ 0	$ 0
Variable Interest Entity [Abstract]
Subsidiary trusts owned by parent | subsidiarytrusts	3
Amortization period of LIH investments	10 years
Income taxes	$ (46,624,000)	(49,921,000)	$ (52,606,000)
Stock Options
Property, Plant and Equipment [Line Items]
Term of award	P10Y
LIH Low Income Housing
Variable Interest Entity [Abstract]
Income taxes	$ 14,600,000	10,400,000
Other Assets
Variable Interest Entity [Abstract]
Investments in low income housing	186,400,000	$ 175,000,000
Other Noncurrent Liabilities
Variable Interest Entity [Abstract]
Investments, in low income housing, additional commitments	$ 40,600,000
Building and Building Improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	50 years
Furniture and Fixtures
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	8 years
Equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	5 years
Consumer Loan
Property, Plant and Equipment [Line Items]
Number of days closed end consumer loans are charged off when they become past due	120 days
Number of days open end consumer loans are charged off when they become past due	180 days