Share Based Award Share based compensation (Details) (Employee Stock Option [Member], USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options, Outstanding, Number	2,556,936	1,952,124
Options, Outstanding, Weighted Average Exercise Price	$ 49.46	$ 39.26
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term	7 years 0 months
Options, Outstanding, Intrinsic Value	$ 82,936
Options, Grants in Period, Gross	1,192,560
Options, Grants in Period, Weighted Average Exercise Price	$ 58.91
Options, Exercises in Period	(529,181)
Options, Exercises in Period, Weighted Average Exercise Price	$ 32.78
Options, Nonvested Options Forfeited, Number of Shares	(58,567)
Options, Nonvested Options Forfeited, Weighted Average Grant Date Fair Value	$ 52.51
Options, Vested, Number of Shares	1,193,223
Exercise Price Range, Exercisable Options, Weighted Average Exercise Price	$ 39.19
Options, Exercisable, Weighted Average Remaining Contractual Term	4 years 8 months
Options, Exercisable, Intrinsic Value	50,963
Options, Vested and Expected to Vest, Exercisable, Number	2,556,936
Options, Vested and Expected to Vest, Outstanding, Weighted Average Exercise Price	$ 49.46
Options, Vested and Expected to Vest, Outstanding, Weighted Average Remaining Contractual Term	7 years 0 months
Options, Vested and Expected to Vest, Outstanding, Aggregate Intrinsic Value	$ 82,936