Accrued Expenses Accrued Expenses Footnote (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($)
Concentration Risk [Line Items]
Accrued expenses classified as liabilities held for sale	$ 0.8
Total Current Liabilities
Concentration Risk [Line Items]
Benchmark for individual components of accrued expenses, percentage	5.00%