Income Taxes - Deferred Tax Valuation Allowance (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Changes in estimated realization of deferred tax assets	$ 600	$ 2,400
Balance at Beginning Period	5,826	3,393	$ 3,530
Charge to cost and expense	1,839	5,654	1,081
Deductions	1,272	3,221	1,218
Balance at end of period	$ 6,393	$ 5,826	$ 3,393