Outstanding Commitments and Contingent Liabilities (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Dec. 31, 2016
Credit Commitments and Contingencies
Liabilities for potential obligations under guarantees	$ 0	$ 0
Maximum
Credit Commitments and Contingencies
Term for guarantee	1 year
Commitments to extend credit
Credit Commitments and Contingencies
Financial instruments whose contract amounts represent credit risk	$ 953,244	875,077
Standby letters of credit
Credit Commitments and Contingencies
Financial instruments whose contract amounts represent credit risk	$ 19,168	$ 20,145