Significant Accounting Policies - Additional Information (Details)	12 Months Ended
	Dec. 31, 2016 USD ($) Office Factor Region	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Number of offices | Office	193
Percentage of remaining principal balance of the loan servicer repurchase (in hundredths)	100.00%
Number of days to pass to be classified as past due LHFI	30 days
Balance of commercial nonaccrual loans identified for impairment analysis, minimum	$ 500,000
Components in allowance for loan losses methodology | Factor	3
Key market regions | Region	5
Impairment losses on premises and equipment	$ 750,000	$ 0	$ 0
Finite-lived intangible assets, average useful life	20 years
Securities with limited marketability	$ 71,000,000	62,600,000
Excess tax expense paid for shares withheld for tax-withholding purpose	107,000	$ 211,000	$ 195,000
Cash paid for shares withheld for tax-withholding purpose	1,000,000
Total outstanding operating lease obligation	$ 58,050,000
Percentage of total outstanding operating lease obligation of total assets	0.40%
Designated as Hedging Instrument [Member] | Interest Rate Swap [Member]
Summary Of Significant Accounting Policies [Line Items]
Variable interest rate, description	three-month LIBOR
Period for which cash flow hedges will be used to hedge quarterly interest payments	5 years
Credit Card Loans [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of days past due loans are to be charged-off	180 days
Commercial Credits [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of days past due for loan to be classified as nonaccrual	90 days
Non-Business Purpose Credits [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of days past due for loan to be classified as nonaccrual	120 days
Number of days past due loans are to be charged-off	120 days
Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of days mortgage LHFS are retained on balance sheet	30 days
Minimum [Member] | Furniture and Equipment [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives of the assets	3 years
Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of days mortgage LHFS are retained on balance sheet	45 days
Period for which cash flow hedges will be used to hedge quarterly interest payments		90 days
Maximum [Member] | Buildings [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives of the assets	39 years
Maximum [Member] | Furniture and Equipment [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives of the assets	10 years
Maximum [Member] | 1-4 Family Residential Real Estate [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of days past due loans are to be charged-off	180 days