Share Tracking Award Plans (Details) (USD $)	12 Months Ended
	Dec. 31, 2013 Share tracking award plans (STAP)	Dec. 31, 2012 Share tracking award plans (STAP)	Dec. 31, 2011 Share tracking award plans (STAP)	Dec. 31, 2013 Share tracking award plans (STAP) Minimum	Jan. 30, 2014 2011 share tracking awards plan (STAP)	Dec. 31, 2013 2011 share tracking awards plan (STAP)
Awards granted under the STAP
Share-based awards, vesting period	4 years			1 year
Grant expiration period from the grant date	10 years
Aggregate STAP liability	$ 305,200,000
Long term portion of STAP liability	17,200,000
Number of awards remained available for grant						1,000,000
Additional increase in total number of awards available for grant (in shares)					3,000,000
Expected volatility maximum period	5 years
Assumptions used to measure the fair value of STAP awards
Expected volatility (as a percent)	32.70%	32.80%	38.00%
Risk-free interest rate (as a percent)	1.10%	0.50%	0.50%
Expected term of awards	3 years 10 months 24 days	3 years 8 months 12 days	3 years 10 months 24 days
Expected forfeiture rate (as a percent)	10.10%	8.70%	7.00%
Expected dividend yield (as a percent)	0.00%	0.00%	0.00%
Share-based awards activity
Outstanding at the beginning of the period (in shares)	7,962,375
Granted (in shares)	3,372,994
Exercised (in shares)	(2,049,136)
Forfeited (in shares)	(551,332)
Outstanding at the end of the period (in shares)	8,734,901	7,962,375
Exercisable at the end of the period (in shares)	3,277,377
Expected to vest at the end of the period (in shares)	4,895,737
Share awards, Weighted-Average Exercise Price
Outstanding at the beginning of the period (in dollars per share)	$ 49.00
Granted (in dollars per share)	$ 57.55
Exercised (in dollars per share)	$ 43.55
Forfeited (in dollars per share)	$ 62.16
Outstanding at the end of the period (in dollars per share)	$ 52.75	$ 49.00
Exercisable at the end of the period (in dollars per share)	$ 47.50
Expected to vest at the end of the period (in dollars per share)	$ 55.95
Share awards, Weighted Average Remaining Contractual Term
Outstanding at the end the period	7 years 8 months 12 days
Exercisable at the end of the period	6 years 2 months 12 days
Expected to vest at the end of the period	8 years 6 months
Share awards, Aggregate Intrinsic Value
Outstanding at the end of the period (in dollars)	526,976,000
Exercisable at the end of the period (in dollars)	214,929,000
Expected to vest at the end of the period (in dollars)	$ 279,704,000
Awards granted during the period, weighted average grant date fair value (in dollars per share)	$ 24.78	$ 21.28	$ 27.80