Income Taxes - Reconciliation of effective tax rate (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Expected income tax expense (benefit) computed on pre-tax income at weighted average income tax rate	$ 110,337	$ 158,269	$ 111,947
Addition (reduction) in income tax expense (benefit) resulting from:
Investment income	(12,762)	(23,572)	(1,824)
State taxes, net of U.S. federal tax benefit	10,650	20,978	5,027
Dividend withholding taxes	10,559	12,211	7,105
Change in valuation allowance	(22,726)	(40,425)	13,190
Base eroding tax	7,694	0	0
Share based compensation	(9,159)	(5,339)	(2,533)
Tax credits	(9,736)	0	0
Intercompany loan write-off	(3,544)	0	(22,083)
Other	(1,352)	6,460	1,009
Income tax expense	$ 79,961	$ 128,582	$ 111,838

Effective Income Tax Reconciliation, Intercompany Loan Writeoff, Amount

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The portion of the difference, between total income tax expense or benefit as reported in the Income Statement for the year/accounting period and the expected income tax expense or benefit computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations, that is attributable to withholding taxes on dividends.

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Amount of reported income tax expense from difference to expected income tax expense (benefit) computed by applying domestic federal statutory income tax rate to pretax income (loss) from continuing operations, attributable to base erosion and anti-abuse tax (BEAT).

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Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to tax credits. Including, but not limited to, research credit, foreign tax credit, investment tax credit, and other tax credits.

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