Fair Value Measurements - Nonrecurring (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2017	Dec. 31, 2016	Mar. 31, 2017	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015
Assets and liabilities measured at fair value
Valuation allowance	$ 98	$ 1,049
Carrying value of other real estate owned	11,724	11,916	$ 13,481	$ 16,252	$ 17,745	$ 19,141
OREO Valuation allowance	8,304	9,982	$ 9,659	$ 13,377	$ 14,399	$ 14,127
Nonrecurring
Assets and liabilities measured at fair value
Total	11,866	11,916
Nonrecurring | Impaired loans
Assets and liabilities measured at fair value
Total	142
Valuation allowance	98	1,000
Increase (decrease) of specific allocations within the provision for loan losses	705	1,000
Nonrecurring | Other real estate owned
Assets and liabilities measured at fair value
Total	11,724	11,916
Carrying value of other real estate owned	11,700	11,900
Outstanding balance	21,600	23,500
OREO Valuation allowance	8,300	10,000
OREO participations	1,600	1,600
Nonrecurring | Level 3
Assets and liabilities measured at fair value
Total	11,866	11,916
Nonrecurring | Level 3 | Impaired loans
Assets and liabilities measured at fair value
Total	142
Nonrecurring | Level 3 | Other real estate owned
Assets and liabilities measured at fair value
Total	$ 11,724	$ 11,916