Fair Value (Transfers between Levels of the Fair Value Hierarchy) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Fair Value Transfers Between Level 1, Level 2 and Level 3 [Line Items]
Transfers from Level 2 to Level 1	$ 0	$ 0
Transfers from Level 3 to Level 1	0	0
Transfers from Level 1 to Level 2	0	0
Transfers from Level 3 to Level 2	0	2
Transfers from Level 1 to Level 3	0	0
Transfers from Level 2 to Level 3	$ 0	$ 0