Income Tax Expense - Valuation Allowance (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income tax (expense) benefit
Balance at beginning of year	$ (116,200)	$ (103,185)	$ (100,832)
Balance at end of year	(118,583)	(116,200)	(103,185)
Tax benefit
Income tax (expense) benefit
Change in valuation allowance	$ (2,383)	$ (13,015)	$ (2,353)