Stockholder's Equity and Statutory Accounting Principles - Additional Information (Detail) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Policyholders Account In Life Insurance Business [Abstract]
Statutory net income (loss)	$ 78,057	$ (53,324)
Statutory capital and surplus	774,251		$ 696,073
Cash dividend paid	0	75,000
Return of capital to Transamerica Corporation /TA Corp	$ 44,840	$ 13,501