Debt and Credit Facilities (Borrowing Obligations) (Detail) (USD $)	Jun. 30, 2014	Sep. 30, 2013
Debt Instrument [Line Items]
Total long-term debt	$ 2,375,955,000	$ 2,354,131,000
Less: current portion	253,547,000	246,040,000
Non-current portion of long-term debt	2,122,408,000	2,108,091,000
5.375% Senior Notes due August 15, 2020
Debt Instrument [Line Items]
Debt instrument, stated interest rate	5.375%	5.375%
Debt Instrument, Interest Rate, Effective Percentage	5.28%	5.28%
Unamortized Premium	4,800,000	5,400,000
Senior Notes, net of unamortized premium	1,054,797,000	1,055,385,000
2.75% Convertible Debentures due August 15, 2027
Debt Instrument [Line Items]
Debt instrument, stated interest rate	2.75%	2.75%
Debt Instrument, Interest Rate, Effective Percentage	7.30%	7.30%
Debt instrument, unamortized discount	(1,300,000)	(8,800,000)
Convertible Debentures, net of unamortized discount	248,713,000	241,206,000
Convertible Debentures Two Point Seven Five Percent Due November One Twenty Thirty One [Member]
Debt Instrument [Line Items]
Debt instrument, stated interest rate	2.75%	2.75%
Debt Instrument, Interest Rate, Effective Percentage	7.43%	7.43%
Debt instrument, unamortized discount	(95,100,000)	(113,500,000)
Convertible Debentures, net of unamortized discount	594,878,000	576,524,000
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Debt instrument, unamortized discount	(1,000,000)	(1,200,000)
Credit Facility, net of unamortized original issue discount of $1.0 million and $1.2 million respectively.	$ 477,567,000	$ 481,016,000