Unaudited condensed consolidated statements of stockholders' equity or deficit - shares - shares shares in Millions	Preferred Stock Including Additional Paid in Capital	Common Stock Including Additional Paid in Capital
Beginning balance at Dec. 31, 2019	20.7	572.8
Stock option exercises and other common stock transactions		2.1
Ending balance at Mar. 31, 2020	20.7	574.9
Beginning balance at Dec. 31, 2020	20.7	580.1
Stock option exercises and other common stock transactions		1.7
Ending balance at Mar. 31, 2021	20.7	581.8