Fair Value Measurements - Estimated Fair Values of Financial Instruments (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2013	Dec. 31, 2012
Fair Value Disclosures [Abstract]
Cash and cash equivalents, Carrying Amount	$ 764,034	$ 118,702	$ 427,711	$ 640,147
Restricted cash and cash equivalents, Carrying Amount	189,871	23,652
Investments, Carrying Amount	4,219	13,511
Debt, Carrying Amount	(904,375)	(88,562)
Forward contracts, Carrying Amount	(2,614)	(28,767)
Cash and cash equivalents, Fair Value	764,034	118,702
Restricted cash and cash equivalents, Fair Value	189,871	23,652
Investments, Fair Value	4,219	13,511
Debt, Fair Value	(932,590)	(90,005)
Forward contracts, Fair Value	$ (2,614)	$ (28,767)