Long-term Debt - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended			9 Months Ended			9 Months Ended			3 Months Ended	6 Months Ended	9 Months Ended					9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013 HealthCare Partners (HCP)	Sep. 30, 2013 Interest rate swap agreements	Sep. 30, 2013 Interest rate cap agreements	Sep. 30, 2013 Term Loan A	Sep. 30, 2013 Term Loan A Interest rate swap agreements Contract	Sep. 30, 2013 Term Loan A-3	Sep. 30, 2013 Term Loan B	Mar. 31, 2013 Term Loan B Interest rate cap agreements	Jun. 30, 2013 Term Loan B Interest rate cap agreements	Sep. 30, 2013 Term Loan B Interest rate cap agreements Contract	Sep. 30, 2013 Term Loan B Interest rate cap agreements Maximum	Sep. 30, 2013 Term Loan B-2	Sep. 30, 2013 Term Loan B-2 Interest rate cap agreements	Sep. 30, 2013 Term Loan A-3	Sep. 30, 2013 Term Loan A-3 Interest rate swap agreements	Sep. 30, 2013 Letter of Credit
Debt Instrument [Line Items]
Debt instrument principal payment								$ 75,000		$ 50,625	$ 13,125					$ 12,375
Interest rate agreements, notional amount						600,000			825,000					1,250,000			1,485,000		1,299,375
Fixed interest rate, lower limit						0.72%			1.59%										0.49%
Fixed interest rate, upper limit						0.75%			1.64%										0.52%
Weighted average effective interest rate									4.36%										3.01%
Interest rate margin in effect									2.75%										2.50%
Cap agreements, expiration date						Sep. 30, 2016	Sep. 30, 2016		Sep. 30, 2014					Sep. 30, 2014					Sep. 30, 2016
Debt expense recognized							1,220		9,383					2,691					2,145
Fair value of assets						1,676	8,838							4					3,909
Unrealized pre-tax losses in other comprehensive income									10,759										3,511
Swap rate agreement effective date						2014-09-30
Debt Instrument interest LIBOR Rate							2.50%								4.00%
Unrealized loss in other comprehensive income	(7,733)	(1,741)	1,583	(6,104)			302					(3)
Number of interest rate agreements									9					5
Total liability fair value									10,759
Ineffective cash flow hedges loss													59	59
Debt instrument face amount											1,250,000					1,485,000
LIBOR interest rate for interest cap																2.50%
Overall weighted average effective interest rate on Senior Secured Credit Facilities	4.18%		4.18%
Current margin in effect								2.75%		2.50%	3.00%					3.00%		2.50%
Weighted average effective interest rate			4.87%
Overall weighted average effective interest rate	4.86%		4.86%
Undrawn revolving credit facilities	350,000		350,000																	99,000
Outstanding letter of credit					$ 1,000