Income Taxes - Narratives (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Taxes
Tax Cuts And Jobs Act Of 2017, deferred tax benefits realized	$ 6,600,000
Accrued interest related to uncertain tax position	0	$ 0
Deferred tax asset	31,800,000	33,000,000
Deferred tax liability	30,524,000	32,655,000
Deferred tax assets, valuation allowance	26,300,000	28,100,000
Operating loss carryforward, federal	48,900,000	35,100,000
Operating loss carry forward, state	31,900,000	21,300,000
Operating loss carry forward, foreign	$ 40,500,000	19,900,000
Minimum
Income Taxes
Open tax year	2016
Minimum | Federal
Income Taxes
Operating loss carryforwards, expiration date	Dec. 31, 2032
Minimum | State and Local
Income Taxes
Operating loss carryforwards, expiration date	Dec. 31, 2027
Maximum
Income Taxes
Open tax year	2011
Equity Method Investments
Income Taxes
Deferred tax expense	$ 2,600,000	$ 4,000,000	$ 2,300,000