Long-term Debt - Additional Information (Detail) - USD ($)	1 Months Ended			12 Months Ended
	Oct. 31, 2015	Apr. 30, 2015	Jun. 30, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Debt Instrument [Line Items]
Payment of total outstanding principal balances under existing Senior Secured Credit Facilities plus accrued interest				$ 53,922,290,000	$ 60,046,487,000	$ 66,723,385,000
Debt refinancing charge				48,072,000	97,548,000
Senior notes				4,500,000,000	3,775,000,000
Maximum additional borrowing capacity			$ 1,500,000,000
Debt expense recognized				389,755,000	385,750,000	401,140,000
Unrealized (losses) gain on interest rate swap and cap agreements				$ (12,241,000)	(10,059,000)	169,000
Weighted average effective interest rate				4.39%
Weighted average effective interest rate				4.42%
Amortization of deferred financing costs				$ 18,625,000	24,544,000	$ 28,803,000
HealthCare Partners (HCP)
Debt Instrument [Line Items]
Outstanding letters of credit				1,286,000
Letter of Credit
Debt Instrument [Line Items]
Outstanding letters of credit				92,238,000
Revolving Credit Facility
Debt Instrument [Line Items]
Facility, aggregate principal amount			$ 1,000,000,000
Facility, term			5 years
Interest rate cap agreements
Debt Instrument [Line Items]
Interest rate agreements, notional amount				$ 7,000,000,000
Derivative, effective date				Jun. 29, 2018
Interest Rate Cap Agreements Effective September 30, 2016
Debt Instrument [Line Items]
Interest rate agreements, notional amount				$ 3,500,000,000
Derivative, effective date				Sep. 30, 2016
Derivative, expiration date				Jun. 30, 2018
Fair value of assets				$ 1,312,000
Unrealized (losses) gain on interest rate swap and cap agreements				$ (11,029,000)
Amortizing Swap
Debt Instrument [Line Items]
Notional amount			$ 1,137,500,000
Interest rate swap agreements
Debt Instrument [Line Items]
Notional amount			$ 600,000,000
Interest rate swap agreements | Not Designated as Hedging Instrument
Debt Instrument [Line Items]
Debt instrument, variable interest rate margin				1.75%
Notional amount				$ 165,000,000
Interest Rate Cap Agreements Effective June 29, 2018
Debt Instrument [Line Items]
Interest rate agreements, notional amount	$ 3,500,000,000
Derivative, expiration date	Jun. 30, 2020
Fair value of assets				13,815,000
Unrealized (losses) gain on interest rate swap and cap agreements				(3,492,000)
Maximum
Debt Instrument [Line Items]
Senior secured leverage ratio			3.50
Minimum
Debt Instrument [Line Items]
Senior secured leverage ratio			1.00
Term Loan A
Debt Instrument [Line Items]
Debt instrument, annual principal payment				$ 50,000,000	62,500,000
Term Loan A | Interest rate swap agreements
Debt Instrument [Line Items]
Debt instrument, variable interest rate margin				1.75%
Notional amount				$ 760,000,000
Weighted average effective interest rate				2.26%
Derivative, expiration date				Sep. 30, 2016
Debt expense recognized				$ 2,664,000
Fair value of asset, net				516,000
Amount of gains (losses) recognized in OCI on swaps arising during the period net of tax				(3,971,000)
Unrealized pre-tax gains in other comprehensive income				516,000
Term Loan B
Debt Instrument [Line Items]
Debt instrument, annual principal payment				35,000,000	21,875,000
Term Loan B | Interest rate cap agreements
Debt Instrument [Line Items]
Interest rate agreements, notional amount				$ 2,735,000,000
Derivative, expiration date				Sep. 30, 2016
Debt expense recognized				$ 2,439,000
Unrealized (losses) gain on interest rate swap and cap agreements				$ (1,593,000)
Term Loan B | Maximum | Interest rate cap agreements
Debt Instrument [Line Items]
Debt instrument, variable interest rate margin				3.50%
LIBOR interest rate for interest cap				3.50%
Term Loan B | Maximum | Interest rate cap agreements | Derivative Instrument 1
Debt Instrument [Line Items]
Debt instrument Interest rate				2.50%
Interest rate agreements, notional amount				$ 2,735,000,000
Remaining outstanding debt				$ 712,500,000
Derivative, Floor Interest Rate				0.75%
Term Loan B | Minimum
Debt Instrument [Line Items]
Debt instrument Interest rate				0.75%
Senior Secured Credit Facilities
Debt Instrument [Line Items]
Payment of total outstanding principal balances under existing Senior Secured Credit Facilities plus accrued interest				$ 5,362,400,000
Undrawn revolving credit facilities				$ 1,000,000,000
Weighted average effective interest rate				3.46%
Term Loan A Term Loan B
Debt Instrument [Line Items]
Interest rate description				At December 31, 2015, the overall weighted average interest rate for the Term Loan A was determined based upon the LIBOR interest rates in effect for all of the individual tranches plus the interest rate margin.
Term Loan A Term Loan B | Maximum
Debt Instrument [Line Items]
Term Loan A and Term Loan B maturity date range				12 months
Term Loan A Term Loan B | Minimum
Debt Instrument [Line Items]
Term Loan A and Term Loan B maturity date range				1 month
Senior Notes 5.125 Percent Due 2024
Debt Instrument [Line Items]
Senior note, interest rate			5.125%	5.125%
Senior note, due date				2024
Debt Instrument, frequency of periodic payment				The 5 1/8% Senior Notes pay interest on January 15 and July 15
Senior notes				$ 1,750,000,000
Senior Notes 6.375 Percent Due 2018
Debt Instrument [Line Items]
Senior notes, principal balance				$ 775,000,000
Term Loan A-3
Debt Instrument [Line Items]
Debt instrument, annual principal payment					16,875,000
Term Loan B-2
Debt Instrument [Line Items]
Debt instrument, annual principal payment					$ 4,125,000
Senior Notes 5.0 Percent Due 2025
Debt Instrument [Line Items]
Senior note, interest rate		5.00%		5.00%
Senior note, due date		2025		2025
Debt Instrument, frequency of periodic payment				The 5.0% Senior Notes pay interest on May 1 and November 1
Senior notes, principal balance		$ 1,500,000,000
Senior notes				$ 1,500,000,000
Senior notes interest payment, first required payment date		Nov. 01, 2015
Debt instrument, redemption description				The Company may redeem up to 35% of the 5.0% Senior Notes at any time prior to May 1, 2018 at a certain specified price from the proceeds of one or more equity offerings. In addition, the Company may redeem some or all of the 5.0% Senior Notes at any time prior to May 1, 2020 at make whole redemption rates and on or after such date at certain specified redemption prices.
Senior Notes 5.0 Percent Due 2025 | Senior Notes Redemption Period One
Debt Instrument [Line Items]
End date of debt instrument redemption period		May 01, 2018
Senior Notes 5.0 Percent Due 2025 | Senior Notes Redemption Period Two
Debt Instrument [Line Items]
End date of debt instrument redemption period		May 01, 2020
Senior Notes 5.0 Percent Due 2025 | Maximum
Debt Instrument [Line Items]
Debt Instrument, redemption price percentage		35.00%
Senior Notes 5.75 Percent Due 2022
Debt Instrument [Line Items]
Senior note, interest rate				5.75%
Senior note, due date				2022
Senior notes				$ 1,250,000,000
Senior Notes 6.625 Percent Due 2020
Debt Instrument [Line Items]
Senior note, interest rate		6.625%
Senior note, due date				2020
Senior notes, principal balance		$ 775,000,000
Debt redemption and refinance charges				$ 48,072,000
New Term Loan A
Debt Instrument [Line Items]
Facility, aggregate principal amount			$ 1,000,000,000
Facility, term			5 years
New Term Loan B
Debt Instrument [Line Items]
Facility, aggregate principal amount			$ 3,500,000,000
Facility, term			7 years
London Interbank Offered Rate (LIBOR) | Interest Rate Cap Agreements Effective September 30, 2016
Debt Instrument [Line Items]
LIBOR cap rate				3.50%
London Interbank Offered Rate (LIBOR) | Interest Rate Cap Agreements Effective June 29, 2018
Debt Instrument [Line Items]
LIBOR cap rate	3.50%
London Interbank Offered Rate (LIBOR) | Term Loan A
Debt Instrument [Line Items]
Debt instrument, variable interest rate margin				1.75%
London Interbank Offered Rate (LIBOR) | Term Loan A | Interest rate swap agreements
Debt Instrument [Line Items]
Fixed interest rate, lower limit				0.49%
Fixed interest rate, upper limit				0.52%
London Interbank Offered Rate (LIBOR) | Term Loan B
Debt Instrument [Line Items]
Debt instrument, variable interest rate margin				2.75%
LIBOR cap rate				2.50%
London Interbank Offered Rate (LIBOR) | Term Loan B | Maximum
Debt Instrument [Line Items]
Debt instrument, variable interest rate margin					2.75%
London Interbank Offered Rate (LIBOR) | Term Loan B | Minimum
Debt Instrument [Line Items]
Debt instrument, variable interest rate margin				2.75%