Commitments and Contingencies (Narrative) (Details) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2017 USD ($) properties	Mar. 31, 2016 USD ($)	Dec. 31, 2016
Commitments and Contingencies Disclosure [Abstract]
Number of non-cancelable operating leases | properties	251
Rent expense	$ 9,800	$ 9,700
Rent income	513	$ 503
Standby letters of credit that expire within one year	50,400
Standby letters of credit that expire thereafter	19,500
Standby letters of credit, fees	154
Residential mortgage loan repurchase reserve liability	$ 1,100
Days past due of GNMA loans available for repurchase	90 days
GNMA Loans past due by 90 days, but not yet repurchased	$ 5,300
Concentration risk, percentage	75.00%		76.00%