Supplemental Information about Changes to Accumulated Other Comprehensive Income - Schedule of Change in Balance by Component of Accumulated Other Comprehensive Income (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), Beginning Balance	$ 925,275
Other comprehensive income (loss) before reclassifications, net of tax	(716,918)
Reclassifications, net of tax	2,624
Other comprehensive income (loss)	(714,294)	375,359	526,824
Accumulated other comprehensive income (loss), Ending Balance	210,981	925,275
Pension Adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), Beginning Balance	(109,283)
Other comprehensive income (loss) before reclassifications, net of tax	33,992
Reclassifications, net of tax	11,938
Other comprehensive income (loss)	45,930
Accumulated other comprehensive income (loss), Ending Balance	(63,353)
Foreign Exchange [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), Beginning Balance	26,608
Other comprehensive income (loss) before reclassifications, net of tax	(1,742)
Reclassifications, net of tax	0
Other comprehensive income (loss)	(1,742)
Accumulated other comprehensive income (loss), Ending Balance	24,866
Deferred Acquisition Costs [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), Beginning Balance	(16,417)
Other comprehensive income (loss) before reclassifications, net of tax	9,689
Reclassifications, net of tax	0
Other comprehensive income (loss)	9,689
Accumulated other comprehensive income (loss), Ending Balance	(6,728)
Available for Sale Assets [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), Beginning Balance	1,024,367
Other comprehensive income (loss) before reclassifications, net of tax	(758,857)
Reclassifications, net of tax	(9,314)
Other comprehensive income (loss)	(768,171)
Accumulated other comprehensive income (loss), Ending Balance	$ 256,196