Deferred Policy Acquisition Costs - Balances and Activity in DAC Roll Forward (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Deferred Policy Acquisition Cost [Line Items]
DAC balance, beginning of period	$ 3,194,029
Amortization	(67,358)	$ (63,223)
DAC balance, end of period	3,256,845		$ 3,194,029
Term Life [Member]
Deferred Policy Acquisition Cost [Line Items]
DAC balance, beginning of period	3,111,675	2,872,816	2,872,816
Capitalization	127,293		507,834
Amortization	(65,503)		(252,352)
Foreign exchange translation and other	830		(16,623)
DAC balance, end of period	3,174,295		3,111,675
Segregated Funds (Canada) [Member]
Deferred Policy Acquisition Cost [Line Items]
DAC balance, beginning of period	62,341	$ 65,411	65,411
Capitalization	1,834		7,003
Amortization	(1,493)		(5,581)
Foreign exchange translation and other	181		(4,492)
DAC balance, end of period	$ 62,863		$ 62,341