Non-controlling Interest - Narrative (Details) - USD ($)		3 Months Ended	9 Months Ended		12 Months Ended
	Jan. 01, 2018	Dec. 31, 2017	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2017	Dec. 31, 2016
Significant Accounting Policies [Line Items]
Percentage of cash savings in federal, state and local taxes to be paid in cash under tax receivable agreements			85.00%
Current portion of payable pursuant to tax receivable agreements			$ 6,135,000			$ 13,235,000
Amounts paid pursuant to Tax Receivable Agreements (TRAs)			7,296,000	$ 1,344,000
Statutory federal rate (as a percent)					35.00%
Provision for income taxes		$ 40,900,000
Benefit as a result of reduction in TRA Liability		32,700,000
Net effect on net income		$ 8,200,000
Scenario, Forecast
Significant Accounting Policies [Line Items]
Statutory federal rate (as a percent)	21.00%
RIHI
Significant Accounting Policies [Line Items]
Liability representing the payments due pursuant to tax receivable agreements			91,985,000
Current portion of payable pursuant to tax receivable agreements			$ 6,135,000