Accounts Payable (Details) - USD ($) $ in Millions	Dec. 31, 2017	Mar. 31, 2017
Accounts Payable [Abstract]
Checks Issued In Excess Of Associated Bank Balances But Not Yet Presented For Collection	$ 103	$ 69

Checks Issued In Excess Of Associated Bank Balances But Not Yet Presented For Collection

No definition available.

Name:	s_ChecksIssuedInExcessOfAssociatedBankBalancesButNotYetPresentedForCollection
Namespace Prefix:	s_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant