Fair Values of Financial Instruments - Estimated Fair Values of Financial Instruments (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2013	Dec. 31, 2012
Fair Value Disclosures [Abstract]
Cash and cash equivalents, Carrying Amount	$ 268,130	$ 118,702	$ 461,535	$ 640,147
Restricted cash and cash equivalents, Carrying Amount	43,286	23,652
Investments, Carrying Amount	5,437	13,511
Debt, Carrying Amount	(308,178)	(88,562)
Forward contracts, Carrying Amount	(14,995)	(28,767)
Cash and cash equivalents, Fair Value	268,130	118,702
Restricted cash and cash equivalents, Fair Value	43,286	23,652
Investments, Fair Value	5,437	13,511
Debt, Fair Value	(309,430)	(90,005)
Forward contracts, Fair Value	$ (14,995)	$ (28,767)