Tax Receivable Agreement Liability - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Income Tax Contingency [Line Items]
Reduction in federal, state, local and non-US income taxes (in percentage)	90.00%
Liability for tax receivable agreement	$ 203.8
Liability for tax receivable agreement balance	135.8	$ 135.8
Current Liability
Income Tax Contingency [Line Items]
Liability for tax receivable agreement	$ 15.9	$ 15.9