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, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Components Of Other Comprehensive Income Loss [Line Items]
Marketable securities, Balance at beginning of period	$ 117,245	$ 107,834	$ 105,419	$ 186,451
Marketable securities, Unrealized gain (loss) arising during the year	59,716	(482)	71,542	(79,099)
Marketable securities, Balance at end of period	176,961	107,352	176,961	107,352
Currency translation, Balance at beginning of period	(139,439)	(137,447)	(135,165)	(133,041)
Other comprehensive income (loss)	4,155	8,286	(119)	3,880
Currency translation, Balance at end of period	(135,284)	(129,161)	(135,284)	(129,161)
Balance at beginning of period	(86,603)	(86,892)	(95,253)	(4,724)
Other comprehensive income (loss)	64,419	8,222	73,069	(73,946)
Balance at end of period	(22,184)	(78,670)	(22,184)	(78,670)
Defined Benefit Pension Plans
Components Of Other Comprehensive Income Loss [Line Items]
Balance at beginning of period	(65,016)	(58,347)	(66,402)	(59,478)
Other comprehensive income (loss)-amortization of prior service credit and net gains/losses included in net periodic pension cost	692	556	2,078	1,687
Balance at end of period	(64,324)	(57,791)	(64,324)	(57,791)
OPEB
Components Of Other Comprehensive Income Loss [Line Items]
Balance at beginning of period	607	1,068	895	1,344
Other comprehensive income (loss)-amortization of prior service credit and net gains/losses included in net periodic pension cost	(144)	(138)	(432)	(414)
Balance at end of period	$ 463	$ 930	$ 463	$ 930