Subsequent Events (Narrative) (Details) ₨ in Billions	Oct. 21, 2015 USD ($) site system	Oct. 21, 2015 INR (₨) site system	Oct. 28, 2015 USD ($)	Sep. 30, 2015 USD ($)
Credit Facility 2013 | Revolving Credit Facility
Subsequent Event [Line Items]
Debt covenant, threshold on indebtedness				$ 250,000,000
Credit Facility 2014 | Revolving Credit Facility
Subsequent Event [Line Items]
Debt covenant, threshold on indebtedness				250,000,000
Term Loan 2013 | Unsecured Debt
Subsequent Event [Line Items]
Debt covenant, threshold on indebtedness				$ 250,000,000
Subsequent Event | Viom Transaction
Subsequent Event [Line Items]
Number of sites acquired | site	42,200	42,200
Distributed antenna systems acquired | system	200	200
Percentage of voting interests acquired	51.00%	51.00%
Aggregate purchase price	$ 1,157,000,000	₨ 76
Subsequent Event | Credit Facility 2013 | Revolving Credit Facility
Subsequent Event [Line Items]
Debt covenant, threshold on indebtedness			$ 300,000,000
Subsequent Event | Credit Facility 2014 | Revolving Credit Facility
Subsequent Event [Line Items]
Debt covenant, threshold on indebtedness			300,000,000
Subsequent Event | Term Loan 2013 | Unsecured Debt
Subsequent Event [Line Items]
Debt covenant, threshold on indebtedness			$ 300,000,000