Stockholders' Equity (Details Textual) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Class of Stock [Line Items]
Allocated Share-based Compensation Expense	$ 9.6	$ 5.6	$ 16.3	$ 10.0
Stockholders' Equity (Textual) [Abstract]
Share price (in dollars per share)	$ 189.25		$ 189.25
Total intrinsic value of options exercised	$ 9.4	31.8	$ 20.1		$ 120.2
Employee stock options [Member]
Stockholders' Equity (Textual) [Abstract]
Unrecognized compensation cost related to unvested options	48.3		$ 48.3
Period in which compensation expense will generally be recognized ratably			2 years 1 month
RSU [Member]
Stockholders' Equity (Textual) [Abstract]
Intrinsic value of released units	99.2	$ 112.1	$ 163.5	$ 234.5
Unrecognized compensation cost	$ 1,100.0		$ 1,100.0
Period in which compensation expense will generally be recognized ratably			2 years 11 months
Class A Common Stock [Member]
Stockholders' Equity (Textual) [Abstract]
Shares outstanding (in shares)	119,163,762		119,163,762		116,468,385
Class B Common Stock [Member]
Stockholders' Equity (Textual) [Abstract]
Shares outstanding (in shares)	15,559,383		15,559,383		15,580,510
RSUs and other equity [Member]
Stockholders' Equity (Textual) [Abstract]
Shares authorized (in shares)	0		394,094
Shares outstanding	726,194		726,194
Unrecognized compensation cost	$ 33.1		$ 33.1
Period in which compensation expense will generally be recognized ratably			2 years 4 months 28 days