Income Taxes - Tax Receivable Agreement (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2017	Dec. 31, 2016
Tax Receivable Agreement
Cash savings percentage (as a percent)	85.00%
Benefits of cash savings retained under tax receivable agreement (as a percent)	15.00%
Increase (decrease) in TRA liability due to valuation allowance recorded	$ (33,200)	$ (2,700)
Liability under tax receivable agreement	11,807	43,045
Valuation allowance	14,500	$ 50,600
Anticipated payment	$ 600