Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2021

Equity [Abstract]

Schedule of Common Stock Activity

The following table summarizes Common Stock activity during the periods presented below:

	Year Ended December 31,
	2021	2020	2019
	(In millions)
Shares outstanding at the beginning of the period	97.8	96.9	110.4
Shares issued for vested restricted stock units	1.0	1.3	1.5
Shares issued in exchange for debt retirement	10.0	—	—
Shares issued under at-the-market equity offering program	24.8	—	—
Shares repurchased	(0.3)	(0.4)	(15.0)
Shares outstanding at the end of the period	133.3	97.8	96.9