Allowance for Expected Credit Losses - Contractholder receivables (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2021	Dec. 31, 2020
Credit Loss [Abstract]
Balance at beginning of period		$ 1,986,924	$ 2,119,460
Balance at end of period		1,828,691	1,986,924
Allowance for Expected Credit Losses
Balance at beginning of period		8,638	0
Cumulative effect of accounting change	[1]		6,663
Change for provision of expected credit losses		(5,201)	1,975
Balance at end of period		$ 3,437	$ 8,638

[1] Adoption of ASU 2016-13, “Financial Instruments - Credit Losses (Topic 326)”