Fair Value Measurements - Nonrecurring (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Assets and liabilities measured at fair value
Valuation allowance	$ 1,049,000	$ 34,000
Carrying value of other real estate owned	11,916,000	19,141,000	$ 31,982,000	$ 41,537,000
OREO Valuation allowance	9,982,000	14,127,000	$ 19,229,000	$ 22,284,000
Nonrecurring
Assets and liabilities measured at fair value
Total	11,916,000	19,222,000
Nonrecurring | Impaired loans
Assets and liabilities measured at fair value
Total		81,000
Valuation allowance		34,000
Increase (decrease) of specific allocations within the provision for loan losses	1,000,000	(243,000)
Nonrecurring | Impaired loans | Carrying Amount
Assets and liabilities measured at fair value
Total	1,000,000	115,000
Nonrecurring | Other real estate owned
Assets and liabilities measured at fair value
Total	11,916,000	19,141,000
Outstanding balance	23,500,000	34,900,000
OREO Valuation allowance	10,000,000	14,100,000
OREO participations	1,600,000	1,700,000
Nonrecurring | Level 3
Assets and liabilities measured at fair value
Total	11,916,000	19,222,000
Nonrecurring | Level 3 | Impaired loans
Assets and liabilities measured at fair value
Total		81,000
Nonrecurring | Level 3 | Other real estate owned
Assets and liabilities measured at fair value
Total	$ 11,916,000	$ 19,141,000