Deferred Acquisition Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Movement Analysis of Deferred Policy Acquisition Costs
Balance at beginning of year	$ 4,595,444	$ 4,341,941	$ 4,137,925
Deferred during period:
Commissions	678,517	600,577	534,735
Other expenses	227,730	222,408	218,926
Total deferred	906,247	822,985	753,661
Value of business acquired(1)	16,500	0	0
Foreign exchange adjustment	0	4,755	4,299
Adjustment attributable to unrealized investment losses(2)	1,628	1,533	0
Total additions	924,375	829,273	757,960
Amortized during period	(603,838)	(575,770)	(551,726)
Foreign exchange adjustment	(1,253)	0	0
Adjustment attributable to unrealized investment gains(2)	0	0	(2,218)
Total deductions	(605,091)	(575,770)	(553,944)
Balance at end of year	$ 4,914,728	$ 4,595,444	$ 4,341,941