Share-Based Payments (Details 8) (Time-vested restricted stock units, USD $)	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013	Dec. 31, 2012
Time-vested restricted stock units
Time-vested restricted stock units
Beginning Balance, Unvested, Shares	1,660,000
Beginning Balance, Weighted Average Grant Date Fair Value	$ 135.95
Shares, Granted	464,000	[1]
Weighted Average Grant Date Fair Value, Granted	$ 321.72	[1]	$ 176.53	$ 124.54
Shares, Vested	(885,000)
Weighted Average Grant Date Fair Value, Vested	$ 117.74
Shares, Forfeited	(102,000)
Weighted Average Grant Date Fair Value, Forfeited	$ 193.24
Ending Balance, Unvested, Shares	1,137,000		1,660,000
Ending Balance, Weighted Average Grant Date Fair Value	$ 221.01		$ 135.95

[1] RSUs granted in 2014 primarily represent RSUs granted in conjunction with our annual awards made in February 2014 and awards made in conjunction with the hiring of new employees. RSUs granted in 2014 also include approximately 9,000 RSUs granted to our Board of Directors.