Segment Information - General (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2016 USD ($) product segment	Sep. 30, 2015 USD ($)
Net revenues, cost of product sales and gross profits
Number of operating segments | segment			1
Number of commercial products | product			5
Net product sales	$ 408.2	$ 384.7	$ 1,189.8	$ 1,056.4
Cost of product sales	23.6	6.9	44.3	43.7
Gross profit	384.6	377.8	1,145.5	1,012.7
Remodulin
Net revenues, cost of product sales and gross profits
Net product sales	152.4	150.1	451.1	432.3
Cost of product sales	3.7		4.3	7.1
Cost of product sales		(2.2)
Gross profit	148.7	152.3	446.8	425.2
Tyvaso
Net revenues, cost of product sales and gross profits
Net product sales	101.8	121.7	311.0	350.9
Cost of product sales	5.8	3.5	12.9	15.9
Gross profit	96.0	118.2	298.1	335.0
Adcirca
Net revenues, cost of product sales and gross profits
Net product sales	96.0	73.8	259.5	187.3
Cost of product sales	5.5	4.5	15.0	11.2
Gross profit	90.5	69.3	244.5	176.1
Orenitram
Net revenues, cost of product sales and gross profits
Net product sales	40.7	34.4	118.9	81.2
Cost of product sales	5.2	2.1	7.9	7.6
Gross profit	35.5	32.3	111.0	73.6
Unituxin
Net revenues, cost of product sales and gross profits
Net product sales	17.3	4.7	49.3	4.7
Cost of product sales	3.4		4.2	1.9
Cost of product sales		(1.0)
Gross profit	$ 13.9	$ 5.7	$ 45.1	$ 2.8