Long-Term Debt and Capital Lease Obligations - Domestic Line of Credit (Details)		1 Months Ended	12 Months Ended
	May. 10, 2011 USD ($) bank	Jun. 30, 2014 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Sep. 30, 2013 USD ($)	May. 31, 2013 USD ($)
Line of Credit Facility [Line Items]
Repayment of credit facility			$ 0	$ 500,800,000	$ 470,000,000
2.125% cash convertible senior notes due 2019 [Member]
Line of Credit Facility [Line Items]
Stated interest rate		2.125%	2.125%
Domestic Line of Credit [Member]
Line of Credit Facility [Line Items]
Number of banks involved in line of credit facility | bank	5
Maturity period of new credit agreement	4 years
Borrowing capacity	$ 175,000,000					$ 200,000,000
Line of credit potential maximum	$ 225,000,000
Repayment of credit facility		$ 119,400,000