Accumulated Other Comprehensive Income (Loss) (Other Comprehensive Income (Loss) Reclassification Adjustments) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accumulated Other Comprehensive Income Loss [Line Items]
Pretax change before reclassifications	$ (75,538)	$ 105,890	$ (52,520)
Reclassifications out of AOCI	14,899	151,099	71,456
Tax effect	8,105	(94,085)	(10,329)
Total other comprehensive (loss) income, net of tax	(52,534)	162,904	8,607
Unrealized Gains (Losses) on Securities
Accumulated Other Comprehensive Income Loss [Line Items]
Pretax change before reclassifications	(63,910)	101,553	2,617
Reclassifications out of AOCI	14,249	(14,719)	(18,319)
Tax effect	11,243	(23,271)	5,343
Total other comprehensive (loss) income, net of tax	(38,418)	63,563	(10,359)
Foreign Currency Translation Adjustment
Accumulated Other Comprehensive Income Loss [Line Items]
Pretax change before reclassifications	(28,145)	24,744	(6,334)
Reclassifications out of AOCI	0	0	0
Tax effect	1,349	0	0
Total other comprehensive (loss) income, net of tax	(26,796)	24,744	(6,334)
Pension Benefit Adjustment
Accumulated Other Comprehensive Income Loss [Line Items]
Pretax change before reclassifications	16,517	(20,407)	(48,803)
Reclassifications out of AOCI	650	165,818	89,775
Tax effect	(4,487)	(70,814)	(15,672)
Total other comprehensive (loss) income, net of tax	$ 12,680	$ 74,597	$ 25,300