Other Comprehensive Income (Loss) - Schedule of Changes in Accumulated Other Comprehensive Income (Loss) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Components Of Other Comprehensive Income Loss [Line Items]
Marketable securities, Balance at beginning of period	$ 70,238	$ 139,320	$ 154,169	$ 105,419
Marketable securities, Unrealized gains (losses) arising during the year	(22,933)	(22,075)	(106,864)	11,826
Marketable securities, Balance at end of period	47,305	117,245	47,305	117,245
Currency translation, Balance at beginning of period	(134,330)	(140,555)	(133,816)	(135,165)
Other comprehensive income (loss)	(860)	1,116	(1,374)	(4,274)
Currency translation, Balance at end of period	(135,190)	(139,439)	(135,190)	(139,439)
Balance at beginning of period	(119,081)	(66,187)	(35,016)	(95,253)
Total other comprehensive income (loss)	(23,431)	(20,416)	(107,496)	8,650
Balance at end of period	(142,512)	(86,603)	(142,512)	(86,603)
Defined Benefit Pension Plans
Components Of Other Comprehensive Income Loss [Line Items]
Balance at beginning of period	(56,107)	(65,703)	(56,644)	(66,402)
Defined benefit pension plans/ Other postretirement benefit plans	518	687	1,055	1,386
Balance at end of period	(55,589)	(65,016)	(55,589)	(65,016)
OPEB
Components Of Other Comprehensive Income Loss [Line Items]
Balance at beginning of period	1,118	751	1,275	895
Defined benefit pension plans/ Other postretirement benefit plans	(156)	(144)	(313)	(288)
Balance at end of period	$ 962	$ 607	$ 962	$ 607