Schedule II - Valuation and Qualifying Accounts Deferred Tax Assets - (Details) - Valuation allowance for deferred tax assets - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Valuation allowance and reserves
Balance at Beginning of Period	$ 42,504	$ 41,769	$ 42,165
Tax Valuation Allowance Charged to Income Tax Provision	1,049	735
Tax Valuation Allowance Credited to Income Tax Provision			(396)
Balance at End of Period	$ 43,553	$ 42,504	$ 41,769