Other Comprehensive Income (Loss) - Schedule of Changes in Accumulated Other Comprehensive Income (Loss) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Components Of Other Comprehensive Income Loss [Line Items]
Marketable securities, Balance at beginning of period	$ 47,305	$ 117,245	$ 154,169	$ 105,419
Marketable securities, Unrealized gains (losses) arising during the year	1,022	59,716	(105,842)	71,542
Marketable securities, Balance at end of period	48,327	176,961	48,327	176,961
Currency translation, Balance at beginning of period	(135,190)	(139,439)	(133,816)	(135,165)
Other comprehensive income (loss)	(9,215)	4,155	(10,589)	(119)
Currency translation, Balance at end of period	(144,405)	(135,284)	(144,405)	(135,284)
Balance at beginning of period	(142,512)	(86,603)	(35,016)	(95,253)
Total other comprehensive income (loss), net	(7,819)	64,419	(115,315)	73,069
Balance at end of period	(150,331)	(22,184)	(150,331)	(22,184)
Defined Benefit Pension Plans
Components Of Other Comprehensive Income Loss [Line Items]
Balance at beginning of period	(55,589)	(65,016)	(56,644)	(66,402)
Defined benefit pension plans/ Other postretirement benefit plans	530	692	1,585	2,078
Balance at end of period	(55,059)	(64,324)	(55,059)	(64,324)
OPEB
Components Of Other Comprehensive Income Loss [Line Items]
Balance at beginning of period	962	607	1,275	895
Defined benefit pension plans/ Other postretirement benefit plans	(156)	(144)	(469)	(432)
Balance at end of period	$ 806	$ 463	$ 806	$ 463