Results of Operations for Former PSI Facilities Reflected as Discontinued Operations (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Acquisitions And Discontinued Operations [Line Items]
Net revenues	$ 95,226	$ 159,218	$ 126,218
Income from discontinued operations	(3,472)	10,422	12,109
Gain on divestiture	26,419	442	0
Income from discontinued operations, before income tax expense	22,947	10,864	12,109
Income tax expense	(8,688)	(4,113)	(4,483)
Income from discontinued operations, net of income tax expense	$ 14,259	$ 6,751	$ 7,626