Share-Based Compensation (Details) (Employee Stock Option [Member], USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Employee Stock Option [Member]
Equity stock-based compensation
Term of options			10 years
Period of vesting			3 years
Assumptions used to measure the fair value of awards
Expected life			5 years 6 months	5 years 9 months 18 days
Risk-free interest rate (as a percent)			1.63%	1.11%
Expected volatility (as a percent)			30.28%	32.64%
Expected dividend yield (as a percent)			2.82%	1.57%
Stock option activity
Outstanding at the beginning of the period (in shares)			2,849,000
Granted (in shares)			715,000	416,000
Exercised (in shares)			(523,000)
Cancelled (in shares)			(48,000)
Outstanding at the end of the period (in shares)	2,993,000		2,993,000
Exercisable at the end of the period (in shares)	1,938,000		1,938,000
Share options, weighted average exercise price per share
Outstanding at the beginning of the period (in dollars per share)			$ 40.77
Granted (in dollars per share)			$ 59.65
Exercised (in dollars per share)			$ 33.37
Cancelled (in dollars per share)			$ 51.66
Outstanding at the end of the period (in dollars per share)	$ 46.40		$ 46.40
Exercisable at the end of the period (in dollars per share)	$ 38.63		$ 38.63
Share options, aggregate intrinsic value
Options outstanding average remaining contractual life			6 years 4 months 2 days
Options outstanding aggregate intrinsic value	$ 87,961,000		$ 87,961,000
Stock options exercisable average remaining contractual life			4 years 11 months 5 days
Stock options exercisable aggregate intrinsic value	72,008,000		72,008,000
Additional information pertaining to stock options
Cash received from exercise of stock options			17,000,000
Unrecognized compensation cost	11,000,000		11,000,000
Weighted-average period for amortization of unrecognized compensation cost			2 years
Weighted-average grant date fair value of stock options granted (in dollars per share)			$ 12.99	$ 17.87
Total intrinsic value of stock options exercised	$ 6,416,000	$ 2,686,000	$ 21,339,000	$ 17,338,000