Income Taxes - Unrecognized Tax Benefits Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Unrecognized Tax Benefits Reconciliation
Balance at beginning of year	$ 52,986	$ 35,879	$ 24,361
Additions based on tax positions taken during a prior period	8,574	13,018	583
Reductions based on tax positions taken during a prior period	(1,749)	(86)	(1,248)
Additions related to positions taken upon finalization of Tax Act during the current period	0	0	16,506
Additions based on tax positions taken during the current period	5,174	8,926	3,133
Reductions based on tax positions taken during the current period	(831)	(259)	(233)
Reductions related to settlement of tax matters	(538)	0	(136)
Reductions related to a lapse of applicable statute of limitations	(1,413)	(4,492)	(7,087)
Balance at end of year	62,203	52,986	$ 35,879
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued	$ 8,100	$ 5,639