Information about Geographic Areas - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013 Segment	Dec. 31, 2012	Dec. 31, 2011
Revenues from External Customers and Long-Lived Assets [Line Items]
Number of reporting segment									1
Revenues	$ 615,219	$ 431,346	$ 405,139	$ 561,792	$ 306,332	$ 50,104	$ 26,653	$ 30,167	$ 2,013,496	$ 413,256	$ 204,242
United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									1,500,000	341,500	103,900
Norway [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									$ 217,100