Long-Term Debt And Borrowing Arrangements - Additional Information (Detail) (USD $)	12 Months Ended								1 Months Ended	12 Months Ended	1 Months Ended			12 Months Ended		1 Months Ended	12 Months Ended		1 Months Ended	12 Months Ended	1 Months Ended	12 Months Ended			1 Months Ended			12 Months Ended	1 Months Ended	12 Months Ended	1 Months Ended	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2012 Uncommitted Credit Facility Maximum	Dec. 31, 2012 Uncommitted Credit Facility Minimum	Dec. 31, 2012 Senior Unsecured Loan Agreement	Dec. 31, 2012 Senior Unsecured Loan Agreement Maximum	Dec. 31, 2012 Senior Unsecured Loan Agreement Minimum	Dec. 31, 2012 3 1/2% Convertible Senior Notes	Dec. 31, 2012 3 1/2% Convertible Senior Notes Maximum	Mar. 31, 2010 9 5/8% Senior Notes	Dec. 31, 2012 9 5/8% Senior Notes	Mar. 31, 2012 Floating Rate Term Loan Due April 2014	Oct. 31, 2010 Floating Rate Term Loan Due April 2014	Mar. 31, 2010 Floating Rate Term Loan Due April 2014	Dec. 31, 2012 Floating Rate Term Loan Due May 2016	Oct. 31, 2011 Floating Rate Term Loan Due May 2016	Oct. 31, 2012 Floating Rate Term Loan Due March 2019	Dec. 31, 2012 Floating Rate Term Loan Due March 2019	Mar. 31, 2012 Floating Rate Term Loan Due March 2019	Apr. 30, 2006 Floating Rate Senior Notes	Dec. 31, 2012 Floating Rate Senior Notes	Apr. 30, 2006 7 5/8% And 7 3/4% Senior Notes	Dec. 31, 2012 7 5/8% Senior Notes	Dec. 31, 2010 7 5/8% Senior Notes	Dec. 31, 2012 7 3/4% Senior Notes	Mar. 31, 2012 8 1/4% Senior Notes	Nov. 30, 2010 8 1/4% Senior Notes	Oct. 31, 2010 8 1/4% Senior Notes	Mar. 31, 2012 8 1/4% Senior Notes	Oct. 31, 2011 9 3/4% Senior Notes	Dec. 31, 2012 9 3/4% Senior Notes	Nov. 30, 2012 4 7/8% Senior Notes	Dec. 31, 2012 4 7/8% Senior Notes
Debt Instrument [Line Items]
Issuance price as percentage of face value							100.00%		98.60%										100.00%		100.00%				103.50%	101.00%	100.00%		100.00%		100.00%
Proceeds from issue of senior notes							$ 345,000,000		$ 444,000,000											$ 250,000,000	$ 750,000,000				$ 125,000,000	$ 200,000,000	$ 400,000,000	$ 731,000,000	$ 250,000,000		$ 300,000,000
Convertible senior note principal amount							1,000
Initial conversion rate							$ 16.25
Converted number of common stock shares							61.5385
Maturity date							Oct. 01, 2014
Repurchase price as percentage of principal amount							100.00%
Additional shares issued to settle convertible notes							6,400,000
Additional shares required to issue under the "make-whole" provisions								700,000
Designated shares issued to settle convertible notes							27,600,000
Increase in conversion price per share							$ 22.50
Convertible Senior Note Repurchased							217,000,000
Convertible notes purchase price							257,000,000																	375,000,000
Repayment of term loan												52,000,000	451,000,000
Principal amount repaid											267,000,000
Term loan facility provided															20,000,000			500,000,000
Additional term loan facility provided														30,000,000		200,000,000
Spread over LIBOR														3.00%
Floating rate of interest														3.32%						2.81%
Minimum interest at LIBOR rate				1.00%													1.00%
Margin in addition to LIBOR rate					0.50%	4.375%											3.25%
Aggregate rate of LIBOR rate																	4.25%
Interest rate agreed to pay to lenders																1.00%	1.00%
Loan repayment from proceeds																	420,000,000
Repayments of senior notes																	75,000,000
Basis spread over LIBOR																				250
Periodic payment of interest										Semi-annually on March 15 and September 15 of each year.										February 15, May 15, August 15 and November 15										Semi-annually on March 15 and September 15 of each year.		Semi-annually on May 15 and November 15 of each year
Senior notes, amount redeemed																							175,000,000
Redemption percentage																						100.00%	103.813%	102.583%
Repayment of term loan																						200,000,000
Registration rights agreement, interest on notes	0.50%
Consideration for providing guarantee	14,000,000
Deferred consideration remaining unamortized amount	1,000,000
Uncommitted credit facilities	38,000,000
Credit facilities bearing interest		5.97%	0.42%
Maximum commitment provided				$ 250,000,000