Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred income tax assets
Tax Receivable Agreement	$ 167,117	$ 101,594
Share-based compensation	9,419	5,213
Intangibles	12,738	14,547
Fixed assets and other	21,088	13,425
Tax credits and net operating loss carryforwards	44,972	50,867
Less: Valuation allowance on net operating loss carryforwards and tax credits	(44,947)	(43,544)
Total deferred income tax assets	210,387	142,102
Deferred income tax liabilities
Intangibles	10,028	16,342
Total deferred income tax liabilities	$ 10,028	$ 16,342