Segments and Geographic Area Analysis - Countries Where Parent Company had Material Concentration of Operating Assets (Parenthetical) (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Entity Wide Disclosure On Geographic Areas Countries Where Parent Company Had Material Concentration Of Operating Assets [Line Items]
Construction work-in-progress	$ 990,964	$ 504,805
South Korea [Member]
Entity Wide Disclosure On Geographic Areas Countries Where Parent Company Had Material Concentration Of Operating Assets [Line Items]
Construction work-in-progress	741,100	490,200
United States [Member]
Entity Wide Disclosure On Geographic Areas Countries Where Parent Company Had Material Concentration Of Operating Assets [Line Items]
Construction work-in-progress	$ 167,400	$ 14,600