Stock-based Compensation (Details 2) (Performance Shares [Member], USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012	Dec. 31, 2011
Performance Shares [Member]
Schedule of information on stock units
Undistributed, Beginning Balance	0.7
Undistributed, Weighted-Average Grant Date Fair Value per Share, Beginning Balance	$ 39.06
Granted	0.1
Granted, Weighted-Average Grant Date Fair Value per Share	$ 78.00		$ 48.64	$ 31.78
Additional shares earned	0.1
Additional shares earned, Weighted-Average Grant Date Fair Value per Share	$ 44.85
Distributed	(0.2)
Distributed, Weighted-Average Grant Date Fair Value per Share	$ 35.26
Forfeited	0
Forfeited, Weighted-Average Grant Date Fair Value per Share	$ 0.00
Undistributed, Ending Balance	0.7	[1]	0.7
Undistributed, Weighted-Average Grant Date Fair Value per Share, Ending Balance	$ 47.83	[1]	$ 39.06

[1] Undistributed performance share units include approximately 0.5 million units with a weighted-average grant date fair value of $47.81 per share that had not yet vested and 0.2 million units that have vested but were not yet distributed.