Schedule of Debt Outstanding (Parenthetical) (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Unamortized debt issuance costs	$ 9,318,000	$ 9,831,000
Term Loan Due in July 2020
Debt Instrument [Line Items]
Debt interest rate	2.50%	2.30%
Debt maturity date	Jul. 31, 2020
Interest payable dates	Interest payable periodically at variable interest rates.
Unamortized debt issuance costs	$ 400,000	$ 400,000
Senior Notes 4.625% Due 2023
Debt Instrument [Line Items]
Stated interest rate	4.625%
Debt maturity date	May 01, 2023
Interest payable dates	Interest payable semi-annually in May and November at 4.625%.
Unamortized debt issuance costs	$ 3,800,000	3,900,000
Senior Notes 4.125% Due 2020
Debt Instrument [Line Items]
Stated interest rate	4.125%
Debt maturity date	Apr. 01, 2020
Interest payable dates	Interest payable semi-annually in April and October at 4.125%.
Unamortized debt issuance costs	$ 2,500,000	2,700,000
Senior Notes 5.0% Due 2022
Debt Instrument [Line Items]
Stated interest rate	5.00%
Debt maturity date	Oct. 15, 2022
Interest payable dates	Interest payable semi-annually in April and October at 5.0%.
Unamortized debt issuance costs	$ 2,600,000	2,800,000
Revolving Credit Facility | $900.0 Million Revolving Credit Facility
Debt Instrument [Line Items]
Line of credit facility maximum borrowing capacity	$ 900,000,000	$ 900,000,000
Revolving Credit Facility maturity date	Jul. 31, 2020
Weighted average rate	2.50%	2.20%
Interest payable dates	Interest payable periodically at variable interest rates.