Fair Value of Financial Instruments - Derivative Fair Value Measurements, Narrative (Details) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Fair Value Disclosures [Abstract]
Total derivative assets valued with prices provied by models and other valuation techniques (as a percent)	13.00%
Total derivative liabilities valued with prices provied by models and other valuation techniques (as a percent)	12.00%
Credit reserve		$ 10

Total of allowances and reserves, the valuation and qualifying accounts that are either netted against the cost of an asset (in order to value it at its carrying value) or that reflect a liability established to represent expected future costs.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 4
-Subparagraph (SX 210.12-09)
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24092-122690

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