Borrowings - Additional Information (Detail)			1 Months Ended			3 Months Ended	12 Months Ended
	Oct. 03, 2013 EUR (€)	Oct. 03, 2013 EUR (€)	Mar. 31, 2014 USD ($)	Mar. 31, 2013 USD ($)	Jan. 31, 2013 USD ($)	Mar. 31, 2013 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Total Debt [Line Items]
Maximum borrowing capacity in term loan							$ 25,000,000
Borrowing capacity							750,000,000.0
Maximum borrowing							1,138,700,000	$ 1,140,200,000
Senior notes principal amount							125,600,000	243,600,000
Principal amount							17,314,000,000	16,361,500,000
Interest expense							58,000,000	55,700,000	$ 45,500,000
Accumulated other comprehensive loss related to cash flow hedges							$ 8,800,000
3.875% senior notes due 2023
Total Debt [Line Items]
Loan maturity							Feb. 01, 2023
Senior notes principal amount					$ 500,000,000.0
Interest rate on senior notes (as a percent)					3.875%
Senior notes percentage of par value					99.966%
Frequency of repayment of debt							semi-annually on February 1 and August 1
Date of first required interest payment							Aug. 01, 2013
Senior notes redemption terms percentage to principal amount							100.00%
Interest expense							$ 19,800,000	19,800,000	18,900,000
Fair value							515,200,000	513,100,000
3.875% senior notes due 2023 | Treasury Rate
Total Debt [Line Items]
Weighted average interest rate for outstanding liquidity arrangements for certain CLOs (as a percent)					30.00%
5.625% senior notes due 2043
Total Debt [Line Items]
Loan maturity			Mar. 30, 2043	Mar. 30, 2043
Senior notes principal amount			$ 200,000,000.0	$ 400,000,000		$ 400,000,000
Interest rate on senior notes (as a percent)			5.625%	5.625%		5.625%
Principal amount			$ 400,000,000.0
Senior notes percentage of par value			104.315%	99.583%		99.583%
Date of first required interest payment				Sep. 30, 2013
Senior notes redemption terms percentage to principal amount				100.00%
Interest expense							33,700,000	31,600,000	$ 17,100,000
Fair value							$ 646,600,000	$ 699,200,000
5.625% senior notes due 2043 | Treasury Rate
Total Debt [Line Items]
Weighted average interest rate for outstanding liquidity arrangements for certain CLOs (as a percent)				40.00%
Senior Credit Facility Term Loan Due 5/05/2020
Total Debt [Line Items]
Loan maturity							May 05, 2020	May 05, 2020
Maximum borrowing							$ 25,000,000	$ 25,000,000
Revolving Credit Facility
Total Debt [Line Items]
Maximum percentage of applicable margin in addition to base rate							0.75%
Maximum percentage of applicable margin							1.75%
Minimum percentage of applicable margin							1.37%
Term Loan Principal and Interest Due in Quarterly Installment
Total Debt [Line Items]
Loan maturity							May 05, 2020
Term loan principal prepaid						$ 475,000,000.0
New Term Loan
Total Debt [Line Items]
Maximum borrowing	€ 12,600,000.0	€ 12,600,000.0					$ 13,700,000
Maturity period (in years)	5 years
New Term Loan | EURIBOR
Total Debt [Line Items]
Weighted average interest rate for outstanding liquidity arrangements for certain CLOs (as a percent)		1.75%					1.75%
Interest Rate Swaps Second [Member]
Total Debt [Line Items]
Derivative maturity date							Sep. 30, 2016
Interest Rate Swaps Second [Member] | Revolving Credit Facility
Total Debt [Line Items]
Notional amount				$ 225,000,000		$ 225,000,000
Interest Rate Swap [Member]
Total Debt [Line Items]
Loan maturity							Sep. 30, 2016
Notional amount							$ 250,000,000