Stock-Based Compensation Options (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Options Outstanding [Abstract]
Outstanding at beginning of year	969,332
Granted	358,469
Exercised	(326,494)
Expired	(2,138)
Forfeited	(15,889)
Outstanding at end of year	983,280	969,332
Vested or expected to vest at end of year	980,480
Exercisable at end of year	442,575
Weighted Average Exercise Price [Abstract]
Beginning of year	$ 54.32
Granted	$ 98.31
Exercised	$ 32.67
Expired	$ 42.44
Forfeited	$ 89.82
End of year	$ 76.99	$ 54.32
Vested or expected to vest at end of year	$ 76.94
Exercisable at end of year	$ 58.91
Weighted Average Remaining Contractual Term, Outstanding at end of year	3 years 1 month 6 days
Weighted Average Remaining Contractual Term, Vested or expected to vest at end of year	3 years 1 month 6 days
Weighted Average Remaining Contractual Term, Exercisable at end of year	1 year 10 months 24 days
Aggregate Intrinsic Value, Outstanding at end of year	$ 15,941,000
Aggregate Intrinsic Value, Vested or expected to vest at end of year	15,940,000
Aggregate Intrinsic Value, Exercisable at end of year	13,836,000
Weighted average grant date fair value of options	$ 18.90	$ 22.16	$ 16.25
Total intrinsic value of options exercised during the year	$ 20,900,000	$ 17,600,000	$ 17,300,000