Stock Compensation - Option activity (Details) - Stock Options	6 Months Ended
	Jun. 30, 2016 $ / shares shares
Shares Available For Grant
Outstanding at the beginning of the period (in shares)	3,846,717
Additional authorization (in shares)	5,000,000
Options granted (in shares)	(1,616,347)
Options cancelled (in shares)	123,975
Outstanding at the end of the period (in shares)	7,354,345
Shares Subject to Outstanding Options, Shares
Outstanding at the beginning of the period (in shares)	11,052,279
Options granted (in shares)	1,616,347
Options exercised (in shares)	(1,132,958)
Options cancelled (in shares)	(123,975)
Options expired (in shares)	(1,834)
Outstanding at the end of the period (in shares)	11,409,859
Shares Subject to Outstanding Options, Weighted Average Exercise Price
Outstanding at the beginning of the period (in dollars per share) | $ / shares	$ 33.55
Options granted (in dollars per share) | $ / shares	92.89
Options exercised (in dollars per share) | $ / shares	17.22
Options cancelled (in dollars per share) | $ / shares	75.68
Options expired (in dollars per share) | $ / shares	3.11
Outstanding at the end of the period (in dollars per share) | $ / shares	$ 43.12