Stock-Based Compensation, Options and Restricted Shares (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
2000 Employee Option Plan
Stock-Based Compensation
Number of additional stock options that can be granted (in shares)	0
Options exercisable period	10 years
2009 Employee Option Plan
Stock-Based Compensation
Common Stock reserved for issuance	58,000,000
Shares available for the granting of additional stock options	12,123,770
Options exercisable period	10 years
Options ratable vesting period	5 years
2004 Directors Option Plan
Stock-Based Compensation
Shares available for the granting of additional stock options	140,000
Options exercisable period	10 years
Number of additional stock options expected to be granted (in shares)	0
Stock Options
Stock option activity
Options outstanding at the beginning of the period (in shares)	32,266,391
Options exercised (in shares)	(834,925)
Options forfeited (in shares)	(45,660)
Options outstanding at the end of the period (in shares)	31,385,806		32,266,391
Vested and non-vested options expected to vest at the end of the period (in shares)	29,778,073
Exercisable at the end of the period (in shares)	12,788,636
Weighted Average Exercise Price
Weighted average exercise price, options outstanding at the beginning of the period (in dollars per share)	$ 44.14
Weighted average exercise price, options outstanding at the end of the period (in dollars per share)	44.54		$ 44.14
Weighted average exercise price, vested and non-vested options expected to vest (in dollars per share)	44.04
Weighted average exercise price, exercisable (in dollars per share)	$ 33.31
Weighted Average Remaining Contractual Term
Weighted average remaining contractual term of options outstanding	6 years 10 months 6 days		7 years 11 days
Weighted average remaining contractual term of options vested options and non-vested expected to vest	6 years 9 months 11 days
Weighted average remaining contractual term of options exercisable	5 years 2 months 12 days
Aggregate Intrinsic Value
Aggregate intrinsic value of options outstanding	$ 835.7		$ 744.1
Aggregate intrinsic value of options, vested and non-vested options expected to vest	807.9
Aggregate intrinsic value of options exercisable	$ 484.2
Status of the Company's non-vested options and changes during the year
Non-vested options at the beginning of the period (in shares)	18,725,570
Non-vested options, options vested (in shares)	(82,740)
Non-vested options, options forfeited (in shares)	(45,660)
Non-vested options at the end of the period (in shares)	18,597,170		18,725,570
Weighted Average Fair Value at Grant Date
Weighted average fair value at the grant date, options outstanding at the beginning of the period (in dollars per share)	$ 7.99
Weighted average fair value at grant date, options vested (in dollars per share)	8.17
Weighted average fair value at grant date, options forfeited (in dollars per share)	7.84
Weighted average fair value at the grant date, options outstanding at the end of the period (in dollars per share)	$ 7.98		$ 7.99
Fair Value at Grant Date
Total intrinsic value of stock options exercised	$ 34.5	$ 20.7
Total fair value of stock options vested	0.7	$ 0.4
Total compensation cost related to non-vested options not yet recognized	$ 101.9
Weighted average expected amortization period	3 years 1 month 17 days
Restricted Shares | 2012 Directors Restricted Stock Plan
Stock-Based Compensation
Shares available for the granting of additional stock options	137,069
Restricted share activity
Restricted shares outstanding at the beginning of the period (in shares)	16,905
Restricted shares outstanding at the end of the period (in shares)	16,905		16,905
Fair Value at Grant Date
Fair value at the grant date, restricted shares outstanding at the beginning of the period (in dollars per share)	$ 57.99
Fair value at the grant date, restricted shares outstanding at the end of the period (in dollars per share)	$ 57.99		$ 57.99
Weighted Average Remaining Amortization Term (in years)	1 month 17 days		4 months 17 days
Total compensation cost related to non-vested restricted shares not yet recognized	$ 0.1
Weighted average expected amortization period	1 month 17 days