Stock-Based Compensation - Exercise Price for Stock Options Outstanding and Exercisable (Details) - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Exercise prices for stock options outstanding and exercisable
Number of stock options outstanding (in shares)	3,904,500
Options Outstanding, Weighted-Average Exercise Price (in dollars per share)	$ 28.03
Stock options
Exercise prices for stock options outstanding and exercisable
Exercise prices, outstanding stock option awards, high end of range (in dollars per share)	$ 80.00
Number of stock options outstanding (in shares)	6,845,685	11,725,823	14,058,574	16,399,870
Options Outstanding, Weighted-Average Remaining Contractual Life	5 years 7 months 10 days
Options Outstanding, Weighted-Average Exercise Price (in dollars per share)	$ 31.13	$ 24.51	$ 21.71	$ 19.04
Number of stock options exercisable	1,965,585	3,299,023	4,799,173
Options Exercisable, Weighted-Average Remaining Contractual Life	4 years 5 months 27 days
Options Exercisable, Weighted-Average Exercise Price (in dollars per share)	$ 26.82	$ 19.64	$ 17.14
Stock options | Range of Exercise Prices $00.00 - $10.00
Exercise prices for stock options outstanding and exercisable
Exercise prices, outstanding stock option awards, high end of range (in dollars per share)	$ 10.00
Number of stock options outstanding (in shares)	242,372
Options Outstanding, Weighted-Average Remaining Contractual Life	2 years 4 months 2 days
Options Outstanding, Weighted-Average Exercise Price (in dollars per share)	$ 6.22
Number of stock options exercisable	242,372
Options Exercisable, Weighted-Average Remaining Contractual Life	2 years 4 months 2 days
Options Exercisable, Weighted-Average Exercise Price (in dollars per share)	$ 6.22
Stock options | Range Of Exercise Prices $10.01 - $20.00
Exercise prices for stock options outstanding and exercisable
Exercise prices, outstanding stock option awards, low end of range (in dollars per share)	10.01
Exercise prices, outstanding stock option awards, high end of range (in dollars per share)	$ 20.00
Number of stock options outstanding (in shares)	1,944,187
Options Outstanding, Weighted-Average Remaining Contractual Life	4 years 5 months 9 days
Options Outstanding, Weighted-Average Exercise Price (in dollars per share)	$ 15.48
Number of stock options exercisable	144,187
Options Exercisable, Weighted-Average Remaining Contractual Life	3 years 8 months 19 days
Options Exercisable, Weighted-Average Exercise Price (in dollars per share)	$ 16.67
Stock options | Range of Exercise Prices $20.01 - $30.00
Exercise prices for stock options outstanding and exercisable
Exercise prices, outstanding stock option awards, low end of range (in dollars per share)	20.01
Exercise prices, outstanding stock option awards, high end of range (in dollars per share)	$ 30.00
Number of stock options outstanding (in shares)	1,903,878
Options Outstanding, Weighted-Average Remaining Contractual Life	4 years 11 months 12 days
Options Outstanding, Weighted-Average Exercise Price (in dollars per share)	$ 26.31
Number of stock options exercisable	1,182,278
Options Exercisable, Weighted-Average Remaining Contractual Life	4 years 6 months
Options Exercisable, Weighted-Average Exercise Price (in dollars per share)	$ 26.09
Stock options | Range of Exercise Prices $30.01 - $40.00
Exercise prices for stock options outstanding and exercisable
Exercise prices, outstanding stock option awards, low end of range (in dollars per share)	30.01
Exercise prices, outstanding stock option awards, high end of range (in dollars per share)	$ 40.00
Number of stock options outstanding (in shares)	1,654,698
Options Outstanding, Weighted-Average Remaining Contractual Life	6 years 8 months 9 days
Options Outstanding, Weighted-Average Exercise Price (in dollars per share)	$ 36.06
Number of stock options exercisable	249,598
Options Exercisable, Weighted-Average Remaining Contractual Life	5 years 9 months 22 days
Options Exercisable, Weighted-Average Exercise Price (in dollars per share)	$ 34.75
Stock options | Range of Exercise Prices $40.01 - $50.00
Exercise prices for stock options outstanding and exercisable
Exercise prices, outstanding stock option awards, low end of range (in dollars per share)	40.01
Exercise prices, outstanding stock option awards, high end of range (in dollars per share)	$ 50.00
Number of stock options outstanding (in shares)	21,400
Options Outstanding, Weighted-Average Remaining Contractual Life	5 years 9 months
Options Outstanding, Weighted-Average Exercise Price (in dollars per share)	$ 44.65
Number of stock options exercisable	8,000
Options Exercisable, Weighted-Average Remaining Contractual Life	3 years 1 month 24 days
Options Exercisable, Weighted-Average Exercise Price (in dollars per share)	$ 42.92
Stock options | Range of Exercise Prices $50.01 - $60.00
Exercise prices for stock options outstanding and exercisable
Exercise prices, outstanding stock option awards, low end of range (in dollars per share)	50.01
Exercise prices, outstanding stock option awards, high end of range (in dollars per share)	$ 60.00
Number of stock options outstanding (in shares)	113,500
Options Outstanding, Weighted-Average Remaining Contractual Life	7 years 26 days
Options Outstanding, Weighted-Average Exercise Price (in dollars per share)	$ 58.09
Number of stock options exercisable	24,000
Options Exercisable, Weighted-Average Remaining Contractual Life	4 years 8 months 16 days
Options Exercisable, Weighted-Average Exercise Price (in dollars per share)	$ 57.92
Stock options | Range of Exercise Prices $60.01 - $70.00
Exercise prices for stock options outstanding and exercisable
Exercise prices, outstanding stock option awards, low end of range (in dollars per share)	60.01
Exercise prices, outstanding stock option awards, high end of range (in dollars per share)	$ 70.00
Number of stock options outstanding (in shares)	945,650
Options Outstanding, Weighted-Average Remaining Contractual Life	8 years 2 months 5 days
Options Outstanding, Weighted-Average Exercise Price (in dollars per share)	$ 66.37
Number of stock options exercisable	95,150
Options Exercisable, Weighted-Average Remaining Contractual Life	7 years 8 months 23 days
Options Exercisable, Weighted-Average Exercise Price (in dollars per share)	$ 64.01
Stock options | Range Of Exercise Prices From Dollars $70.01 - $80.00
Exercise prices for stock options outstanding and exercisable
Exercise prices, outstanding stock option awards, low end of range (in dollars per share)	70.01
Exercise prices, outstanding stock option awards, high end of range (in dollars per share)	$ 80.00
Number of stock options outstanding (in shares)	20,000
Options Outstanding, Weighted-Average Remaining Contractual Life	4 years
Options Outstanding, Weighted-Average Exercise Price (in dollars per share)	$ 72.89
Number of stock options exercisable	20,000
Options Exercisable, Weighted-Average Remaining Contractual Life	4 years
Options Exercisable, Weighted-Average Exercise Price (in dollars per share)	$ 72.89