Consolidated Statement of Changes in Stockholders' Equity - USD ($) shares in Millions, $ in Millions	$0.001 Par Value Common Stock [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Loss [Member]	Retained Earnings [Member]	Total
Balance at Dec. 31, 2015	$ 0.0	$ 318.0	$ (6.4)	$ (2.7)	$ 351.1	$ 660.0
Balance (in shares) at Dec. 31, 2015	39.8		(0.4)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Employee equity plans activity	$ 0.0	34.4		0.0	0.0	34.4
Employee equity plans activity (in shares)	1.2
Separation of Aptevo					(148.4)	(148.4)
Treasury stock			$ 0.0	0.0		0.0
Treasury stock (in shares)			0.0
Net income					51.8	51.8
Other comprehensive income (loss)				(1.6)	0.0	(1.6)
Balance at Dec. 31, 2016	$ 0.0	352.4	$ (6.4)	(4.3)	254.5	596.2
Balance (in shares) at Dec. 31, 2016	41.0		(0.4)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Employee equity plans activity	$ 0.0	28.0		0.0	0.0	28.0
Employee equity plans activity (in shares)	1.1
Shares issued to extinguish convertible notes						238.0
Treasury stock			$ (33.1)	0.0		(33.1)
Treasury stock (in shares)			(0.8)
Net income				0.0	82.6	82.6
Other comprehensive income (loss)				0.6	0.0	0.6
Balance at Dec. 31, 2017	$ 0.1	618.3	$ (39.5)	(3.7)	337.1	912.3
Balance (ASC 606 [Member]) at Dec. 31, 2017	$ 0.1	618.3	$ (39.5)	(3.7)	304.6	$ 879.8
Balance (in shares) at Dec. 31, 2017	50.6		(1.2)			49.4
Balance (in shares) (ASC 606 [Member]) at Dec. 31, 2017	50.6		(1.2)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adoption of new accounting standard (ASC 606), net of tax					(32.5)	$ (32.5)
Employee equity plans activity	$ 0.0	32.6		0.0	0.0	32.6
Employee equity plans activity (in shares)	1.1
Shares issued to extinguish convertible notes	$ 0.1	237.9
Issuance of common stock from acquisition	$ 0.0	37.7				37.7
Issuance of common stock from acquisition (in shares)	0.7
Shares issued to extinguish convertible notes (in shares)	8.5
Treasury stock			$ (0.1)	0.0		(0.1)
Treasury stock (in shares)			0.0
Net income				0.0	62.7	62.7
Other comprehensive income (loss)				(1.8)	0.0	(1.8)
Balance at Dec. 31, 2018	$ 0.1	$ 688.6	$ (39.6)	$ (5.5)	$ 367.3	$ 1,010.9
Balance (in shares) at Dec. 31, 2018	52.4		(1.2)			51.2