Mortgage Banking Activities, Components of Loans Held For Sale (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Schedule of Residential Mortgage Loans Held For Sale [Line Items]
Number of days for past due for loan to be considered nonperforming (in days)	90 days	90 days	90 days
Residential mortgage loans held for sale, nonperforming	$ 0	$ 0	$ 0
Credit losses recognized on residential mortgage loans held for sale	0	0	0
Components of Residential Mortgage Loans Held for Sale [Abstract]
Unpaid principal balance	237,811	309,040	286,414
Residential mortgage loans held for sale, Fair value	237,695	318,191	286,971
Total residential mortgage loans held for sale and mortgage loan commitments, net of forward sales contracts	$ 248,707	$ 332,040	$ 301,897
Not Designated as Hedging Instrument [Member] | Residential mortgage loan commitments [Member]
Schedule of Residential Mortgage Loans Held For Sale [Line Items]
General number of days outstanding for residential mortgage commitments, minimum (in days)	60 days	60 days	60 days
General number of days outstanding for residential mortgage commitments, maximum (in days)	90 days	90 days	90 days
Components of Residential Mortgage Loans Held for Sale [Abstract]
Notional	$ 381,732	$ 902,986	$ 318,359
Derivative, Net fair value	$ 14,267	$ 20,170	$ 9,733
Not Designated as Hedging Instrument [Member] | Forward sales contracts [Member]
Schedule of Residential Mortgage Loans Held For Sale [Line Items]
General number of days for delivery of loans, for which the price is set by forward sales contracts, minimum (in days)	60 days	60 days	60 days
General number of days for delivery for loans, for which the price is set by forward sales contracts, maximum (in days)	90 days	90 days	90 days
Components of Residential Mortgage Loans Held for Sale [Abstract]
Notional	$ 586,517	$ 1,012,041	$ 569,543
Derivative, Net fair value	$ (3,255)	$ (6,321)	$ 5,193