Investment in equity method investees-Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Equity Method Investment Summarized Financial Information Income Statement Abstract
Equity Method Investments	$ 265,524		$ 265,524		$ 246,776
Income Loss From Equity Method Investments			34,214	21,681
Intra- Entity Eliminations [Member] | Equity Method Investments [Member]
Equity Method Investment Summarized Financial Information Income Statement Abstract
Income Loss From Equity Method Investments	24,600	6,300	34,200	21,900
E V E R T E C Inc [Member]
Equity Method Investment Summarized Financial Information Income Statement Abstract
Equity Method Investments	50,155		50,155		101,125
Income Loss From Equity Method Investments	19,070	(45)	18,522	1,685
E V E R T E C Inc [Member] | Before intra-entity eliminations [Member]
Equity Method Investment Summarized Financial Information Income Statement Abstract
Equity Method Investments	$ 63,598		$ 63,598		$ 73,916