Allowance for Loan Losses - Loan Status and Aging of Past Due TDR Loans (Details) - Troubled Debt Restructured Loans - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2016	Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
TDR loans in in-school/grace/deferment	$ 12,937	$ 6,869
TDR loans in forbearance	59,834	43,756
TDR loans in repayment and percentage of each status:
Loans current	292,740	185,936
Total TDR loans in repayment	328,198	215,206
Total TDR loans, gross	$ 400,969	$ 265,831
Loans current, in percentage	89.20%	86.40%
Total TDR loans in repayment, in percentage	100.00%	100.00%
Loans delinquent 31-60 days
TDR loans in repayment and percentage of each status:
Loans delinquent	$ 17,134	$ 14,948
Loans delinquent, in percentage	5.20%	6.90%
Loans delinquent 61-90 days
TDR loans in repayment and percentage of each status:
Loans delinquent	$ 12,150	$ 9,239
Loans delinquent, in percentage	3.70%	4.30%
Loans delinquent greater than 90 days
TDR loans in repayment and percentage of each status:
Loans delinquent	$ 6,174	$ 5,083
Loans delinquent, in percentage	1.90%	2.40%