Debt - Narrative (Detail) (USD $)	12 Months Ended			0 Months Ended	3 Months Ended		0 Months Ended		3 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Apr. 09, 2010	Mar. 31, 2014	Mar. 31, 2012	Aug. 26, 2013	Mar. 14, 2013	Mar. 31, 2013	Mar. 20, 2014	Mar. 13, 2012	Nov. 12, 2013
Debt Instrument [Line Items]
Amount of difference between fair value and book value	$ 259,500,000	$ 343,400,000
Repayment of Debt	811,500,000	830,400,000	625,200,000
Loss on debt extinguishment	(77,100,000)	(81,900,000)	(16,100,000)
Outstanding letters of credit	93,700,000
Interest paid, net of interest received	272,800,000	245,000,000	250,100,000
4.95% Senior Notes Due April 1, 2014
Debt Instrument [Line Items]
Repayment of Debt					258,200,000	341,800,000
Interest rate	4.95%			4.95%		4.95%
Maturity date	Apr. 01, 2014			Apr. 01, 2014		Apr. 01, 2014
6.00% Senior Notes Due due April 1, 2024
Debt Instrument [Line Items]
Interest rate	6.00%
Maturity date	Apr. 01, 2024
Debt instrument, face amount										400,000,000
8.25% Senior Notes Due March 15, 2019
Debt Instrument [Line Items]
Repayment of Debt	211,100,000
Interest rate	8.25%										8.25%
Maturity date	Mar. 15, 2019					Mar. 15, 2019
Debt instrument, face amount	238,900,000										450,000,000
7.25% Senior Notes Due May 15, 2018
Debt Instrument [Line Items]
Repayment of Debt	100,000,000						200,000,000	50,000,000
Interest rate	7.25%
Maturity date	May 15, 2018
7.625% Senior Notes Due June 15, 2020
Debt Instrument [Line Items]
Repayment of Debt	50,000,000
Interest rate	7.625%
Maturity date	Jun. 15, 2020
Debt Instruments Extinguished Three
Debt Instrument [Line Items]
Loss on debt extinguishment	77,100,000
Gain due to termination of related interest rate swaps	2,800,000
6.50% Senior Notes Due November 15, 2023
Debt Instrument [Line Items]
Interest rate	6.50%
Maturity date	Nov. 15, 2023
Debt instrument, face amount												350,000,000
7.00% Senior Notes Due February 15, 2022
Debt Instrument [Line Items]
Interest rate	7.00%
Maturity date	Feb. 15, 2022
Debt instrument, face amount							400,000,000
5.50% Senior Notes Due May 15, 2015
Debt Instrument [Line Items]
Repayment of Debt							100,000,000
Interest rate	5.50%
Maturity date	May 15, 2015
6.125% Senior Notes Due January 15, 2017
Debt Instrument [Line Items]
Repayment of Debt							100,000,000	173,500,000
Interest rate	6.125%
Maturity date	Jan. 15, 2017
Senior Notes Extinguished1
Debt Instrument [Line Items]
Loss on debt extinguishment	46,300,000
7.875% Senior Notes Due March 15, 2021
Debt Instrument [Line Items]
Interest rate	7.875%
Maturity date	Mar. 15, 2021
Debt instrument, face amount								450,000,000
8.60% Senior Notes Due August 15, 2016
Debt Instrument [Line Items]
Repayment of Debt								130,200,000
Interest rate	8.60%
Maturity date	Aug. 15, 2016
Senior Notes Extinguished2
Debt Instrument [Line Items]
Loss on debt extinguishment									35,600,000
Credit Agreements
Debt Instrument [Line Items]
Allowable annual dividend payment under credit agreement	225,000,000
Outstanding letters of credit	56,500,000
Foreign Facilities
Debt Instrument [Line Items]
Total amount of revolving credit agreement	178,300,000
Other Facilities
Debt Instrument [Line Items]
Outstanding letters of credit	91,700,000
Combined Facilities
Debt Instrument [Line Items]
Credit facility borrowings	2,500,000	9,100,000
Revolving Credit Facility
Debt Instrument [Line Items]
Total amount of revolving credit agreement	1,500,000,000
Line of credit facility, expiration date	Sep. 09, 2019
Line of credit facility amendment date	Sep. 09, 2014
Weighted average interest rate on borrowings	2.00%	2.00%
Scenario, Previously Reported | Revolving Credit Facility
Debt Instrument [Line Items]
Total amount of revolving credit agreement	$ 1,150,000,000
Line of credit facility, expiration date	Oct. 15, 2017