Preferred Stock - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions									1 Months Ended	3 Months Ended	6 Months Ended
	Jul. 06, 2020	Jun. 26, 2020	May 27, 2020	May 14, 2020	Mar. 04, 2020	Jun. 28, 2019	Jun. 19, 2019	May 31, 2019	Feb. 07, 2019	Jun. 30, 2020	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Class of Stock [Line Items]
Loss on embedded derivative									$ 0.0	$ 102.6	$ 32.8	$ 0.0
Make-whole provision of embedded derivative										205.2	205.2		$ 172.4
Accretion of redeemable preferred stock										35.1	36.1
Redeemable balance of cumulative preferred stock										$ 1,067.9	$ 1,067.9		$ 0.0
Preferred stock, dividends declared (USD per share)				$ 30.51	$ 30.51			$ 30.51
Aggregate dividends paid on preferred stock		$ 32.1	$ 32.0			$ 10.7	$ 21.3
Subsequent Event
Class of Stock [Line Items]
Make-whole payment for embedded derivative	$ 205.2