Debt (Schedule of Debt Covenants) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015
Line Of Credit Facility Covenant [Member]
Line of Credit Facility [Line Items]
Maximum Leverage Ratio (as a percent)	0.60
Minimum fixed charge coverage ratio	1.50
Minimum tangible net worth	$ 1,910
Secured recourse indebtedness ratio	45.00%
Line Of Credit Facility Covenant Actual Results [Member]
Line of Credit Facility [Line Items]
Maximum Leverage Ratio (as a percent)	0.340
Minimum fixed charge coverage ratio	3.06
Minimum tangible net worth	$ 2,471
Secured recourse indebtedness ratio	34.00%