Income Taxes - Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Reconciliation of the differences between taxes on income (loss) before income taxes
Taxes (benefit) on U.S. and other international earnings (losses) at greater than the Bermuda rate	$ 62,751	$ 54,060	$ 49,375
Increase (decrease) in valuation allowance	(9,759)	32,869	38,822
Tax reserves and interest	861	1,107	(10,626)
State income taxes (benefit)	3,433	3,540	1,698
Total income tax expense (benefit)	$ 57,286	$ 91,576	$ 79,269
Effective tax rate (as a percent)	(8.10%)	(15.50%)	(15.30%)
Office of the Tax Commissioner, Bermuda
Reconciliation of the differences between taxes on income (loss) before income taxes
Effective income tax rate	0.00%