Share-Based Payments (Details 4) - $ / shares		12 Months Ended
		Dec. 31, 2017		Dec. 31, 2016	Dec. 31, 2015
Market stock units activity
Weighted Average Exercise Price, Hemophilia spin-off adjustment		$ 0.00
Market stock units
Market stock units activity
Beginning Balance, Unvested, Shares		230,000
Beginning Balance, Weighted Average Grant Date Fair Value		$ 355.60
Shares, Hemophilia spin-off adjustment		4,000
Weighted Average Exercise Price, Hemophilia spin-off adjustment		$ 0.00
Shares, Granted	[1]	94,000
Weighted Average Grant Date Fair Value, Granted		$ 382.59	[1]	$ 328.03	$ 493.43
Shares, Vested		(112,000)
Weighted Average Grant Date Fair Value, Vested		$ 311.17
Shares, Forfeited		(45,000)
Weighted Average Grant Date Fair Value, Forfeited		$ 372.35
Ending Balance, Unvested, Shares		171,000		230,000
Ending Balance, Weighted Average Grant Date Fair Value		$ 370.83		$ 355.60

[1] MSUs granted in 2017 include approximately 9,000 MSUs issued in 2017 based upon the attainment of performance criteria set for 2013, in relation to awards granted in that year. MSUs granted during 2017 also include awards granted in conjunction with our annual awards made in February 2017 and MSUs granted in conjunction with the hiring of employees. These grants reflect the target number of shares eligible to be earned at the time of grant. MSUs granted in 2017 reflect an adjustment based upon the final performance multiplier in relation to shares granted in 2016, 2015 and 2014.