Long-term debt and cash flow hedges - Additional Information (Detail) (USD $)	3 Months Ended		12 Months Ended				3 Months Ended			12 Months Ended			1 Months Ended	3 Months Ended	1 Months Ended			3 Months Ended																					1 Months Ended						1 Months Ended	3 Months Ended										3 Months Ended							1 Months Ended		3 Months Ended		3 Months Ended
	Mar. 31, 2014	Mar. 31, 2011 Derivative	Dec. 31, 2010 Derivative	Dec. 31, 2013	Oct. 31, 2013	Mar. 31, 2011 One Point Nine One Percent Forward Starting Interest Rate Swaps	Mar. 31, 2011 Two Point Five Zero Percent Forward Starting Interest Rate Swaps	Mar. 31, 2011 One Point Nine Six Percent Forward Starting Interest Rate Swaps	Mar. 31, 2011 One Point Three Two Percent Forward Starting Interest Rate Swaps	Dec. 31, 2010 Two Point Three Eight Percent Forward Starting Interest Rate Swaps	Mar. 31, 2014 Interest Rate Swap	Dec. 31, 2013 Interest Rate Swap	Sep. 29, 2010 7.00% Senior Unsecured Notes	Mar. 31, 2014 7.00% Senior Unsecured Notes	Sep. 29, 2010 7.00% Senior Unsecured Notes Debtor Optional Redemption Period 1	Sep. 29, 2010 7.00% Senior Unsecured Notes Debtor Optional Redemption Period 2	Sep. 29, 2010 7.00% Senior Unsecured Notes Debtor Optional Redemption Period 3	Mar. 31, 2014 Senior Notes 7.125%	Jun. 30, 2008 Senior Notes 7.125%	Jun. 30, 2006 Senior Notes 7.125%	Mar. 31, 2014 Accounts Receivable Securitization Facility	Mar. 31, 2014 Accounts Payable and Accrued Liabilities Interest Rate Swap	Dec. 31, 2013 Accounts Payable and Accrued Liabilities Interest Rate Swap	Mar. 31, 2014 Other Noncurrent Liabilities Interest Rate Swap	Dec. 31, 2013 Other Noncurrent Liabilities Interest Rate Swap	Mar. 31, 2011 Cash Flow Hedging Forward Starting Interest Rate Swaps	Mar. 31, 2011 Cash Flow Hedging One Point Nine One Percent Forward Starting Interest Rate Swaps	Mar. 31, 2011 Cash Flow Hedging Two Point Five Zero Percent Forward Starting Interest Rate Swaps	Mar. 31, 2011 Cash Flow Hedging One Point Nine Six Percent Forward Starting Interest Rate Swaps	Mar. 31, 2011 Cash Flow Hedging One Point Three Two Percent Forward Starting Interest Rate Swaps	Dec. 31, 2010 Cash Flow Hedging Two Point Three Eight Percent Forward Starting Interest Rate Swaps	Mar. 31, 2014 ABR-based loans	Mar. 31, 2014 Amendment of Credit Facility	Mar. 31, 2014 Term Loan- A2	Mar. 31, 2014 Term Loan- A2 One Month Eurodollar Rate Plus Index Based Loans Minimum	Mar. 31, 2014 Term Loan- A2 One Month Eurodollar Rate Plus Index Based Loans Maximum	Mar. 31, 2014 Term Loan- A2 One Two Three Six Month Eurodollar Rate Plus Index Based Loans Minimum	Mar. 31, 2014 Term Loan- A2 One Two Three Six Month Eurodollar Rate Plus Index Based Loans Maximum	Sep. 30, 2012 Term Loan- A2 Amendment of Credit Facility	Mar. 31, 2014 Term Loan- A2 Amendment of Credit Facility	Mar. 31, 2014 Term Loan B Facility	Mar. 31, 2014 Term Loan B Facility One Month Eurodollar Rate Plus Index Based Loans	Mar. 31, 2014 Term Loan B Facility One Two Three Six Month Eurodollar Rate Plus Index Based Loans	Mar. 31, 2014 Term Loan B Facility Amendment of Credit Facility	May 31, 2013 Term Loan B Facility Amendment of Credit Facility Minimum	Mar. 31, 2014 Revolving Credit Facility	Sep. 30, 2012 Revolving Credit Facility	Mar. 31, 2014 Revolving Credit Facility One Month Eurodollar Rate Plus Index Based Loans Minimum	Mar. 31, 2014 Revolving Credit Facility One Month Eurodollar Rate Plus Index Based Loans Maximum	Mar. 31, 2014 Revolving Credit Facility One Two Three Six Month Eurodollar Rate Plus Index Based Loans	Mar. 31, 2014 Revolving Credit Facility One Two Three Six Month Eurodollar Rate Plus Index Based Loans Maximum	Mar. 31, 2014 Revolving Credit Facility Amendment of Credit Facility	Nov. 15, 2010 Revolving Credit Facility Amendment of Credit Facility	Mar. 31, 2014 Revolving Credit Facility Amendment of Credit Facility Extended Maturity	Sep. 30, 2012 Revolving Credit Facility Amendment of Credit Facility Extended Maturity	Mar. 31, 2014 Term Loan A	Sep. 30, 2012 Term Loan A	Mar. 31, 2014 Term Loan A One Month Eurodollar Rate Plus Index Based Loans Minimum	Mar. 31, 2014 Term Loan A One Month Eurodollar Rate Plus Index Based Loans Maximum	Mar. 31, 2014 Term Loan A One Two Three Six Month Eurodollar Rate Plus Index Based Loans Minimum	Mar. 31, 2014 Term Loan A One Two Three Six Month Eurodollar Rate Plus Index Based Loans Maximum	Mar. 31, 2014 Term Loan A Amendment of Credit Facility	Sep. 30, 2012 Term Loan A Amendment of Credit Facility Extended Maturity	May 31, 2013 Tranche B-1 Term Loan Amendment of Credit Facility	Mar. 31, 2014 Tranche B-1 Term Loan Amendment of Credit Facility	Mar. 31, 2014 Short Term on Demand Credit Facility	Mar. 31, 2014 Term Loan-A and Term Loan A2 facilities	Mar. 31, 2013 Term Loan-A and Term Loan A2 facilities
Debt Instrument [Line Items]
Line of credit facility, borrowing capacity																																														$ 800,000,000							$ 800,000,000											$ 745,900,000
Term loan interest rate description																																																																	Borrowings under the Tranche B-1 term loan, which totaled $550 million as of March 31, 2014, bear interest at a rate per annum equal to, at our election, one, two, three or six month LIBOR, plus an applicable margin of 2.25% or ABR plus an applicable margin of 1.25%
Applicable margin percentage on LIBOR																																																																2.25%
Applicable margin percentage on ABR																																																																1.25%
Minimum LIBOR rate for term loan eliminated																																													1.00%
Minimum ABR rate for term loan eliminated																																													2.00%
Line of credit facility amount outstanding																																	3,140,000,000							866,000,000				550,000,000		7,000,000						800,000,000		7,000,000	777,000,000							926,000,000	884,000,000		550,000,000	30,000,000
Borrowing outstanding																																								866,000,000
Line of credit facility, maturity date																																							Aug. 15, 2016							Nov. 15, 2015										Nov. 15, 2015							Aug. 15, 2016
Line of credit facility, available borrowing capacity																																														743,000,000	23,000,000										42,000,000
Letters of credit, outstanding																																	125,000,000													20,000,000
Rate adjustment to weighted average federal funds rate for credit facility borrowings	0.50%
Rate adjustment to one month Eurodollar rate on credit facility borrowings	1.00%
Consolidated leverage ratio																																			0.50%	1.25%	1.50%	2.25%				1.25%	2.25%					0.50%	1.25%	1.50%	2.25%							0.50%	1.25%	1.50%	2.25%
Current applicable margins																																0.50%		1.50%							2.25%					1.50%										1.50%
Scheduled principal payments made																																																																			18,000,000	18,000,000
Installment payments due																																									0																										54,000,000
Quarterly installment payments due in 2015																																																																			77,000,000
Quarterly installment payments due in 2016																																																																			46,000,000
Accounts receivable securitization program credit facility, borrowing capacity					275,000,000
Accounts receivable securitization program credit facility, amount outstanding	160,000,000
Accounts receivable securitization program, additional capacity																					115,000,000
Senior notes, issued													250,000,000							250,000,000
Senior notes, interest rate													7.00%							7.125%
Senior notes, maturity date														Oct. 01, 2018				Jun. 30, 2016
Unsecured Notes make-whole redemption price															103.50%	101.75%	100.00%
Treasury rate plus, basis points													0.50%
Senior notes, repayment terms														Payable semiannually in arrears on April 1st and October 1st of each year				Interest on the 7.125% Notes is payable semiannually in arrears on June 30th and December 30th of each year
Line of credit facility additional borrowing capacity																			150,000,000
Fair value of debt	3,300,000,000
Long-term debt	3,109,158,000			3,209,762,000
Number of additional forward starting interest rate swaps		6	4
Notional amount of interest rate cash flow hedges																										425,000,000	225,000,000	100,000,000	25,000,000	75,000,000	600,000,000
Average fixed rate payable on interest rate swap						1.91%
Fixed rate payable on interest rate swap							2.50%	1.96%	1.32%	2.38%
Maturity date of interest rate cash flow hedges							Dec. 01, 2014	Dec. 01, 2013	Dec. 01, 2012	May 01, 2015
Fair value of our interest rate swaps, liability											$ 20,000,000	$ 24,000,000										$ 18,000,000	$ 19,000,000	$ 2,000,000	$ 5,000,000