Common, Preferred and Treasury Stock - Treasury Stock (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Jun. 18, 2019
Stockholders' Equity Note [Abstract]
Number of shares authorized to be repurchased				100,000,000
Accelerated Share Repurchases [Line Items]
Amount		$ 1,763.0	$ 1,453.0
March 27, 2019 ASR
Accelerated Share Repurchases [Line Items]
Amount		$ 913.0
Shares Repurchased on Repurchase Date		31,779,280
Shares Received from Forward Contract		2,026,584
Total Shares Repurchased		33,805,864
Notional amount		$ 456.5
April 29, 2019 ASR
Accelerated Share Repurchases [Line Items]
Amount		$ 200.0
Shares Repurchased on Repurchase Date		6,015,570
Shares Received from Forward Contract		1,217,805
Total Shares Repurchased		7,233,375
Notional amount		$ 100.0
August 7, 2019 ASR
Accelerated Share Repurchases [Line Items]
Amount		$ 100.0
Shares Repurchased on Repurchase Date		3,150,482
Shares Received from Forward Contract		694,238
Total Shares Repurchased		3,844,720
August 9, 2019 ASR
Accelerated Share Repurchases [Line Items]
Amount		$ 200.0
Shares Repurchased on Repurchase Date		6,405,426
Shares Received from Forward Contract		1,475,487
Total Shares Repurchased		7,880,913
Notional amount		$ 100.0
October 25, 2019 ASR
Accelerated Share Repurchases [Line Items]
Amount		$ 300.0
Shares Repurchased on Repurchase Date		9,020,163
Shares Received from Forward Contract		1,149,121
Total Shares Repurchased		10,169,284
July 29, 2019 through July 30, 2019 Open Market Repurchase
Accelerated Share Repurchases [Line Items]
Amount	$ 50.0
Shares Repurchased on Repurchase Date	1,667,735