Combined Results of Operations (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Business Acquisition, Pro Forma Information [Line Items]
Revenues	$ 166,289	$ 109,490	$ 320,848	$ 202,515
Net income (loss)	$ 40,074	$ 1,137	$ 75,694	$ (11,071)
Net income (loss) per ordinary share - basic	$ 0.70	$ 0.02	$ 1.34	$ (0.21)
Net income (loss) per ordinary share - diluted	$ 0.66	$ 0.02	$ 1.25	$ (0.21)