Unaudited condensed consolidated statements of stockholders' equity or deficit - amounts - USD ($) $ in Millions	Total	Cumulative effect adjustment	Preferred Stock Including Additional Paid in Capital	Common Stock Including Additional Paid in Capital	Accumulated deficit	Accumulated deficit Cumulative effect adjustment	AOCI
Beginning balance at Dec. 31, 2019	$ 2,462.2	$ (1.6)	$ 1,003.7	$ 1,748.1	$ (203.7)	$ (1.6)	$ (85.9)
Comprehensive income (loss)	(20.4)				47.0		(67.4)
Stock-based compensation expense	9.2			9.2
Accumulation of yield on preferred stock	(16.1)			(16.1)
Stock option exercises and other common stock transactions	6.8			6.8
Ending balance at Mar. 31, 2020	2,440.1		1,003.7	1,748.0	(158.3)		(153.3)
Beginning balance at Dec. 31, 2020	2,674.3		1,003.7	1,737.6	(88.7)		21.7
Comprehensive income (loss)	126.2				164.0		(37.8)
Stock-based compensation expense	10.8			10.8
Accumulation of yield on preferred stock	(16.1)			(16.1)
Stock option exercises and other common stock transactions	10.9			10.9
Ending balance at Mar. 31, 2021	$ 2,806.1		$ 1,003.7	$ 1,743.2	$ 75.3		$ (16.1)