Stock-Based Compensation, Stock Option Activity (Details) - Stock Options - USD ($) $ / shares in Units, $ in Millions	3 Months Ended			9 Months Ended	12 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2019	Dec. 31, 2018
Stock option activity
Options outstanding at the beginning of the period (in shares)	38,515,562	34,281,107	35,550,668	35,550,668
Options granted (in shares)	31,000	6,105,700	40,000
Options exercised (in shares)	(589,497)	(1,816,225)	(1,269,121)
Options forfeited (in shares)	(70,910)	(55,020)	(40,440)
Options outstanding at the end of the period (in shares)	37,886,155	38,515,562	34,281,107	37,886,155	35,550,668
Vested and non-vested options expected to vest at the end of the period (in shares)	35,657,175			35,657,175
Exercisable at the end of the period (in shares)	18,810,385			18,810,385
Weighted Average Exercise Price
Weighted average exercise price, options outstanding at the beginning of the period (in dollars per share)	$ 66.22	$ 60.60	$ 59.77	$ 59.77
Weighted average exercise price, options granted (in dollars per share)	96.82	89.55	78.12
Weighted average exercise price, options exercised (in dollars per share)	50.17	38.18	37.30
Weighted average exercise price, options forfeited (in dollars per share)	77.80	78.67	75.17
Weighted average exercise price, options outstanding at the end of the period (in dollars per share)	66.47	$ 66.22	$ 60.60	66.47	$ 59.77
Weighted average exercise price, vested and non-vested options expected to vest (in dollars per share)	65.79			65.79
Weighted average exercise price, exercisable (in dollars per share)	$ 53.76			$ 53.76
Weighted Average Remaining Contractual Term
Weighted average remaining contractual term of options outstanding	6 years 10 months 9 days	7 years 29 days	6 years 8 months 1 day		6 years 9 months 21 days
Weighted average remaining contractual term of options vested options and non-vested expected to vest				6 years 9 months 10 days
Weighted average remaining contractual term of options exercisable				5 years 5 months 4 days
Aggregate Intrinsic Value
Aggregate intrinsic value of options outstanding	$ 1,137.6	$ 1,144.7	$ 1,160.0	$ 1,137.6	$ 798.6
Aggregate intrinsic value of options, vested and non-vested options expected to vest	1,095.1			1,095.1
Aggregate intrinsic value of options exercisable	$ 804.0			$ 804.0