Accumulated Other Comprehensive Income (Loss) (Other Comprehensive Income (Loss) Reclassification Adjustments) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Accumulated Other Comprehensive Income Loss [Line Items]
Pretax change before reclassifications	$ 43,058	$ 61,898
Reclassifications out of AOCI	5,730	7,925
Tax effect	(16,370)	(22,296)
Total other comprehensive income (loss), net of tax	32,418	47,527
Unrealized Gains (Losses) on Securities
Accumulated Other Comprehensive Income Loss [Line Items]
Pretax change before reclassifications	39,624	49,794
Reclassifications out of AOCI	8	2,099
Tax effect	(14,181)	(20,066)
Total other comprehensive income (loss), net of tax	25,451	31,827
Foreign Currency Translation Adjustment
Accumulated Other Comprehensive Income Loss [Line Items]
Pretax change before reclassifications	3,434	12,104
Reclassifications out of AOCI	0	0
Tax effect	0	0
Total other comprehensive income (loss), net of tax	3,434	12,104
Pension Benefit Adjustment
Accumulated Other Comprehensive Income Loss [Line Items]
Pretax change before reclassifications	0	0
Reclassifications out of AOCI	5,722	5,826
Tax effect	(2,189)	(2,230)
Total other comprehensive income (loss), net of tax	$ 3,533	$ 3,596