Segment Information - General (Details) $ in Millions	3 Months Ended		6 Months Ended
Segment Information - General (Details) $ in Millions	Jun. 30, 2025 USD ($)	Jun. 30, 2024 USD ($)	Jun. 30, 2025 USD ($) segment	Jun. 30, 2024 USD ($)
Segment Reporting [Abstract]
Number of operating segments \| segment			1
Net product sales, cost of product sales and gross profit by product
Total revenues	$ 798.6	$ 714.9	$ 1,593.0	$ 1,392.6
Cost of sales	87.6	77.8	180.1	150.7
Gross profit (loss)	711.0	637.1	1,412.9	1,241.9
Tyvaso DPI
Net product sales, cost of product sales and gross profit by product
Total revenues	315.2	258.3	617.7	485.8
Cost of sales	48.5	37.6	96.6	70.9
Gross profit (loss)	266.7	220.7	521.1	414.9
Nebulized Tyvaso
Net product sales, cost of product sales and gross profit by product
Total revenues	154.4	139.9	318.2	284.9
Cost of sales	5.6	8.4	14.1	17.3
Gross profit (loss)	148.8	131.5	304.1	267.6
Remodulin
Net product sales, cost of product sales and gross profit by product
Total revenues	134.7	147.3	272.9	275.3
Cost of sales	14.3	12.8	28.1	20.7
Gross profit (loss)	120.4	134.5	244.8	254.6
Orenitram
Net product sales, cost of product sales and gross profit by product
Total revenues	123.9	107.1	244.6	213.3
Cost of sales	6.7	5.9	15.0	15.1
Gross profit (loss)	117.2	101.2	229.6	198.2
Unituxin
Net product sales, cost of product sales and gross profit by product
Total revenues	58.4	51.7	116.6	110.1
Cost of sales	2.8	3.8	8.0	7.4
Gross profit (loss)	55.6	47.9	108.6	102.7
Adcirca
Net product sales, cost of product sales and gross profit by product
Total revenues	6.5	5.7	12.5	12.1
Cost of sales	2.7	2.6	5.3	5.2
Gross profit (loss)	3.8	3.1	7.2	6.9
Other
Net product sales, cost of product sales and gross profit by product
Total revenues	5.5	4.9	10.5	11.1
Cost of sales	7.0	6.7	13.0	14.1
Gross profit (loss)	$ (1.5)	$ (1.8)	$ (2.5)	$ (3.0)