Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 631,777	$ 160,422	$ 495,607
Other comprehensive income (loss), net of tax
Change in net unrealized gains (losses) on securities	184,156	(136,261)	169,740
Foreign currency transaction and translation adjustments	390	(900)	746
Defined benefit pension plan adjustment	15,495	22,326	15,831
Total other comprehensive income (loss), net of tax	200,041	(114,835)	186,317
Total comprehensive income	831,818	45,587	681,924
Less: Comprehensive income attributable to noncontrolling interest	11,414	1,427	1,956
Total comprehensive income attributable to American National	$ 820,404	$ 44,160	$ 679,968