Accumulated Other Comprehensive Income (Loss) (AOCI) (Components of Accumulated Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated other comprehensive income (loss) including non-controlling interest, Beginning Balance			$ (230,393)
Change in unrealized gains (losses) on securities			81,044
Change in foreign currency translation adjustment			23,558
Net actuarial loss			(8,646)
Amortization of net actuarial loss			15,792
Amortization of prior service credit			(3,268)
Settlement costs			152,388
Tax effect	$ (66,740)	$ (3,399)	(92,235)	$ (38,004)
Accumulated other comprehensive income (loss) including non-controlling interest, Ending Balance	(61,760)		(61,760)
Allocated to the Company	(61,779)		(61,779)		$ (230,400)
Allocated to noncontrolling interests	19		19
Unrealized Gains (Losses) on Securities
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated other comprehensive income (loss) including non-controlling interest, Beginning Balance			(26,760)
Change in unrealized gains (losses) on securities			81,044
Tax effect	(7,976)	(1,169)	(29,030)	(31,303)
Accumulated other comprehensive income (loss) including non-controlling interest, Ending Balance	25,254		25,254
Allocated to the Company	25,235		25,235
Allocated to noncontrolling interests	19		19
Foreign Currency Translation Adjustment
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated other comprehensive income (loss) including non-controlling interest, Beginning Balance			(63,576)
Change in foreign currency translation adjustment			23,558
Tax effect	0	0	0	0
Accumulated other comprehensive income (loss) including non-controlling interest, Ending Balance	(40,018)		(40,018)
Allocated to the Company	(40,018)		(40,018)
Pension Benefit Adjustment
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated other comprehensive income (loss) including non-controlling interest, Beginning Balance			(140,057)
Net actuarial loss			(8,646)
Amortization of net actuarial loss			15,792
Amortization of prior service credit			(3,268)
Settlement costs			152,388
Tax effect	(58,764)	$ (2,230)	(63,205)	$ (6,701)
Accumulated other comprehensive income (loss) including non-controlling interest, Ending Balance	(46,996)		(46,996)
Allocated to the Company	$ (46,996)		$ (46,996)