Share-based Compensation Recognized (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended	12 Months Ended
Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012	Dec. 31, 2011
Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation recognized, net	$ 5,062	$ 134	$ 5,212	$ 291	$ 595	$ 714
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation recognized, net	$ 90	$ 163	$ 271	$ 266	$ 609	$ 170

The amount of expense, net of income tax, recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

No definition available.

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration