Accumulated Other Comprehensive Income (Loss) (Other Comprehensive Income (Loss) Reclassification Adjustments) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Accumulated Other Comprehensive Income Loss [Line Items]
Pretax change before reclassifications	$ (123,674)	$ (19,292)
Reclassifications out of AOCI	(3,251)	3,365
Tax effect	31,555	(4,526)
Total other comprehensive loss, net of tax	(95,370)	(20,453)
Unrealized Gains (Losses) on Securities
Accumulated Other Comprehensive Income Loss [Line Items]
Pretax change before reclassifications	(127,206)	15,396
Reclassifications out of AOCI	(4,615)	2,822
Tax effect	32,075	(5,514)
Total other comprehensive loss, net of tax	(99,746)	12,704
Foreign Currency Translation Adjustment
Accumulated Other Comprehensive Income Loss [Line Items]
Pretax change before reclassifications	3,532	(34,688)
Reclassifications out of AOCI	0	0
Tax effect	(158)	1,132
Total other comprehensive loss, net of tax	3,374	(33,556)
Pension Benefit Adjustment
Accumulated Other Comprehensive Income Loss [Line Items]
Pretax change before reclassifications	0	0
Reclassifications out of AOCI	1,364	543
Tax effect	(362)	(144)
Total other comprehensive loss, net of tax	$ 1,002	$ 399