Long-Term Debt - Long-Term Debt Instrument (Parenthetical) (Detail)	9 Months Ended	12 Months Ended
	Sep. 30, 2014	Dec. 31, 2013
Debt Instrument [Line Items]
Line of credit facility, commitment fee percentage	0.20%
Current Portion of 5-Year Term Loan Facility Expires 2019 [Member]
Debt Instrument [Line Items]
Line of credit facility, expiration period	5 years
Debt instrument maturity year	2019
6.080% Senior Notes, Semi-Annual Interest Payments, Balloon Due 2014 [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage		6.08%
Debt instrument maturity year		2014
5.370% Senior Notes, Quarterly Interest Payments, Balloon Due 2015 [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	5.37%	5.37%
Debt instrument maturity year	2015	2015
5.660% Senior Notes, Semi-Annual Interest Payments, Balloon Due 2016 [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	5.66%	5.66%
Debt instrument maturity year	2016	2016
4.500% Senior Notes, Quarterly Interest Payments, Balloon Due 2018 [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	4.50%	4.50%
Debt instrument maturity year	2018	2018
4.200% Senior Notes, Semi-Annual Interest Payments, Balloon Due 2024 [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	4.20%
Debt instrument maturity year	2024
Periodic Payments of Interest, LIBOR Plus 1.00%, Expires December 31, 2016 [Member]
Debt Instrument [Line Items]
Line of credit facility, expiration date		Dec. 31, 2016
Periodic Payments of Interest, LIBOR Plus 1.00%, Expires December 31, 2016 [Member] \| LIBOR [Member]
Debt Instrument [Line Items]
Debt instrument, variable interest rate		1.00%
Quarterly Payments of Interest, LIBOR Plus 1.00%, Expires December 31, 2016 [Member]
Debt Instrument [Line Items]
Line of credit facility, expiration date		Dec. 31, 2016
Quarterly Payments of Interest, LIBOR Plus 1.00%, Expires December 31, 2016 [Member] \| LIBOR [Member]
Debt Instrument [Line Items]
Debt instrument, variable interest rate		1.00%
Periodic Payments of Interest, LIBOR Plus 1.00%, Expires December 31, 2016 [Member]
Debt Instrument [Line Items]
Line of credit facility, expiration date		Dec. 31, 2016
Periodic Payments of Interest, LIBOR Plus 1.00%, Expires December 31, 2016 [Member] \| LIBOR [Member]
Debt Instrument [Line Items]
Debt instrument, variable interest rate		1.00%
5-Year Term-Loan Facility, Periodic Interest and Principal Payments, Currently LIBOR Plus 1.375%, Expires May 20, 2019
Debt Instrument [Line Items]
Line of credit facility, expiration period	5 years
Line of credit facility, expiration date	May 20, 2019
5-Year Term-Loan Facility, Periodic Interest and Principal Payments, Currently LIBOR Plus 1.375%, Expires May 20, 2019 \| LIBOR [Member]
Debt Instrument [Line Items]
Debt instrument, variable interest rate	1.375%
5-Year Revolving-Loan Facility, Periodic Interest Payments, Currently LIBOR Plus 1.175%, Plus Commitment Fees of 0.20%, Expires May 20, 2019 [Member]
Debt Instrument [Line Items]
Line of credit facility, expiration period	5 years	5 years
Line of credit facility, commitment fee percentage	0.20%	0.20%
Line of credit facility, expiration date	May 20, 2019
5-Year Revolving-Loan Facility, Periodic Interest Payments, Currently LIBOR Plus 1.175%, Plus Commitment Fees of 0.20%, Expires May 20, 2019 [Member] \| LIBOR [Member]
Debt Instrument [Line Items]
Debt instrument, variable interest rate	1.175%	1.175%
Revolving Credit Loan, Quarterly Interest Payments, LIBOR Plus up to 1.40% and Availability Fee up to 0.25%, Expires December 31, 2016 [Member]
Debt Instrument [Line Items]
Line of credit facility, expiration date	Dec. 31, 2016	Dec. 31, 2016
Maximum [Member] \| Revolving Credit Loan, Quarterly Interest Payments, LIBOR Plus up to 1.40% and Availability Fee up to 0.25%, Expires December 31, 2016 [Member]
Debt Instrument [Line Items]
Line of credit facility, commitment fee percentage	0.25%	0.25%
Maximum [Member] \| Revolving Credit Loan, Quarterly Interest Payments, LIBOR Plus up to 1.40% and Availability Fee up to 0.25%, Expires December 31, 2016 [Member] \| LIBOR [Member]
Debt Instrument [Line Items]
Debt instrument, variable interest rate	1.40%	1.40%