Deferred Policy Acquisition Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Balance, beginning of year	$ 4,596,565	$ 4,344,361	$ 749,302
Capitalization of commissions, sales and issue expenses	372,996	277,586	269,679
Amortization-Impact of assumption and experience unlocking and true-ups	(113,534)	288,974	226,204
Amortization-All other	(476,261)	(275,028)	(46,388)
Changes in unrealized investment gains and losses	67,739	(39,328)	18,772
Ceded DAC upon Reinsurance Treaty with Prudential Insurance	0	0	(7,480)
Assumed DAC upon Reinsurance Treaty with Pruco Life	0	0	3,134,272
Balance, end of year	$ 4,447,505	$ 4,596,565	4,344,361
True-up to the ceded DAC upon reinsurance agreement with Prudential Insurance			$ 7,500