Federal Home Loan Bank and Federal Reserve Bank Borrowings (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
FHLB Fixed Rate Advances, Maturities Summary [Abstract]
Federal Home Loan Bank, Advances, Maturities Summary, Average Interest Rate, One To Five Years From Balance Sheet Date	5.66%
FHLB Fixed Rate Advances, Over 1 through 5 years	$ 1,000
FHLB Fixed Rate Advances, Weighted Average Interest Rate, Due after 10 years	5.37%
FHLB Fixed Rate Advances, Due after 10 years	$ 5,000
FHLB Fixed Rate Advances, Total Amount before valuation adjustment	6,000
Valuation adjustment from acquisition accounting	493
FHLB Fixed Rate Advances, Total Amount	6,493
Federal Home Loan Bank, Advances, Activity for Year [Abstract]
FHLB Advances	6,493	$ 68,531	$ 216,568
Average balance during the year	79,673	70,678	44,876
Maximum month-end balance during the year	$ 250,515	$ 242,556	$ 216,568
Weighted average rate during the year	0.80%	0.68%	0.74%
Weighted average rate at December 31	5.42%	0.79%	0.41%
FHLB Advances, Collateral Pledged	$ 1,510,514	$ 1,399,201
FHLB Borrowing Capacity	1,502,284	1,328,971
Federal Reserve Bank, Advances, Activity for Year [Abstract]
Federal Reserve Bank, Advances, Collateral Pledged	61,007	85,428
Federal Reserve Bank borrowing capacity	61,007	85,428
Securities Investment [Member]
Federal Reserve Bank, Advances, Activity for Year [Abstract]
Federal Reserve Bank, Advances, Collateral Pledged	32,795	47,516
Loans Receivable [Member]
Federal Home Loan Bank, Advances, Activity for Year [Abstract]
FHLB Advances, Collateral Pledged	1,510,514	1,399,201
Commercial Loan [Member]
Federal Reserve Bank, Advances, Activity for Year [Abstract]
Federal Reserve Bank, Advances, Collateral Pledged	$ 28,212	$ 37,912