Business, Basis of Presentation and Summary of Significant Accounting Policies (Narrative) (Details) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2016 Segment	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of segments	3	3
Property, Equipment, Leasehold Improvements and Computer Software [Abstract]
Cost basis of computer software		$ 236	$ 254
Accumulated amortization of computer software		136	107
Amortization expense related to computer software		$ 37	$ 1	$ 2
Maximum
Real Estate Held-for-investment And Accumulated Depreciation [Line Items]
Real Estate Held-for-investment And Accumulated Depreciation Life Used For Depreciation		55 years
Minimum
Real Estate Held-for-investment And Accumulated Depreciation [Line Items]
Real Estate Held-for-investment And Accumulated Depreciation Life Used For Depreciation		20 years
Other Capitalized Property Plant and Equipment [Member] | Maximum
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life		7 years
Other Capitalized Property Plant and Equipment [Member] | Minimum
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life		3 years
Leasehold Improvements [Member] | Maximum
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life		10 years
Leasehold Improvements [Member] | Minimum
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life		5 years
Computer Software, Intangible Asset [Member]
Finite-Lived Intangible Assets [Line Items]
Amortization period		4 years
VODA and VOCRA [Member] | Maximum
Finite-Lived Intangible Assets [Line Items]
Amortization period		40 years
VODA and VOCRA [Member] | Minimum
Finite-Lived Intangible Assets [Line Items]
Amortization period		10 years