Debt - Revolving Credit Facility (Details) $ in Millions	Mar. 31, 2016 USD ($)	Feb. 29, 2016 USD ($)
Line of Credit Facility [Line Items]
Line of Credit Facility, maximum borrowing capacity	$ 3,300	$ 3,000
Line of Credit Facility, increase in borrowing capacity	$ 300
Ratio of indebtedness to net capital	0.27
Maximum [Member]
Line of Credit Facility [Line Items]
Ratio of indebtedness to net capital	0.65

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant