Stock-Based Compensation Restricted Stock Awards (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Weighted Average Grant Date Fair Value [Abstract]
Granted	$ 90.30
Restricted stock [Member]
Restricted Stock Shares [Abstract]
Non-vested at beginning of year	270,724
Granted	55,019
Vested	(191,910)
Forfeited	(7,169)
Non-vested at end of year	126,664	270,724
Weighted Average Grant Date Fair Value [Abstract]
Non-vested at beginning of year	$ 59.54
Granted	$ 90.12
Vested	$ 59.05
Forfeited	$ 64.88
Non-vested at end of year	$ 73.25	$ 59.54
Weighted average grant date fair value of restricted stock granted during the year	$ 90.12	$ 65.70	$ 56.03
Total intrinsic value of restricted stock that vested during year	$ 11.3	$ 7.8	$ 4.4