Restatement of Previously Issued Unaudited Financial Statements - Effect of Revisions on affected Line Items on Condensed Consolidated Statement of Cash Flows (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2012
Error Corrections and Prior Period Adjustments Revision [Line Items]
Net income	$ 20,204	$ 45,941	$ 2,932	$ 32,384	$ 106,586
Provision for doubtful accounts	14,924	13,434	30,229		24,088
Deferred income taxes	1,484	(6,490)	(13,899)		(10,714)
Restricted cash	874	842	(638)		485
Accounts receivable	(34,543)	(33,006)	(77,228)		(50,527)
Other operating assets and liabilities	2,121	14,875	8,032		(8,761)
Net cash flows from operating activities	8,802	(37,826)	(35,113)		(1,842)
As Previously Reported [Member]
Error Corrections and Prior Period Adjustments Revision [Line Items]
Net income	20,859	46,002	51,989		107,073
Provision for doubtful accounts	19,038	19,006	38,923		34,607
Deferred income taxes	3,123	(6,334)	16,334		(10,076)
Restricted cash	(57)	372	(175)		1,377
Accounts receivable	(38,037)	(38,270)	(84,686)		(60,176)
Other operating assets and liabilities	(311)	(15,400)	11,004		6,766
Net cash flows from operating activities	7,607	(38,296)	(35,811)		(950)
Consolidation of PEAKS Trust [Member]
Error Corrections and Prior Period Adjustments Revision [Line Items]
Net income	(1,036)	(61)	(49,607)		(487)
Provision for doubtful accounts	0	(5,572)	0		(10,599)
Deferred income taxes	(1,639)	(156)	(26,902)		(638)
Restricted cash	397	470	(500)		(892)
Accounts receivable	0	5,264	0		9,649
Other operating assets and liabilities	(2,049)	525	509		1,995
Net cash flows from operating activities	661	470	661		(892)
Other Adjustments [Member]
Error Corrections and Prior Period Adjustments Revision [Line Items]
Net income	381	45,941	550		106,586
Provision for doubtful accounts	(4,114)	13,434	(8,694)		24,008
Deferred income taxes	0	6,490	(3,331)		(10,714)
Restricted cash	534	842	37		485
Accounts receivable	3,494	(33,006)	7,458		(50,527)
Other operating assets and liabilities	239	(14,875)	(3,482)		8,761
Net cash flows from operating activities	$ 534	$ (37,826)	$ 0		$ (1,842)