Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions		9 Months Ended
		Sep. 30, 2019	Dec. 31, 2018
Assets
Cash and cash equivalents		$ 64.3	$ 62.6
Investments, at fair value		1,996.4	1,576.2
Other receivables		16.3	46.6
Total assets	[1]	2,077.0	1,685.4
Liabilities
Collateralized loan obligation notes, at fair value		1,610.2	1,316.7
Other liabilities		96.1	138.4
Total liabilities	[1]	1,706.3	1,455.1
Fixed maturity securities available for sale, amortized cost		$ 11,104.5	$ 10,834.0
Preferred stock, par value (in dollars per share)		$ 1.00	$ 1.00
Preferred stock, shares authorized (in shares)		2,875,000	2,875,000
Preferred stock, shares issued (in shares)		2,875,000	2,875,000
Preferred stock, shares outstanding (in shares)		2,875,000	2,875,000
Common stock, par value (in dollars per share)		$ 0.01	$ 0.01
Common stock, shares authorized (in shares)		800,000,000	800,000,000
Common Stock, Shares, Issued		161,585,665	161,153,454
Common stock, shares outstanding (in shares)		60,758,742	61,908,979
Treasury stock, at cost (in shares)		100,812,923	99,244,475
Preferred Stock
Liabilities
Share interest rate		6.50%

[1] The following table presents information on assets and liabilities related to consolidated investment entities as of September 30, 2019 and December 31, 2018.   September 30, 2019   December 31, 2018   (in millions) Assets       Cash and cash equivalents $ 64.3
  $ 62.6
Investments, at fair value 1,996.4
  1,576.2
Other receivables 16.3
  46.6
Total assets $ 2,077.0
  $ 1,685.4
Liabilities       Collateralized loan obligation notes, at fair value 1,610.2
  1,316.7
Other liabilities 96.1
  138.4
Total liabilities $ 1,706.3
  $ 1,455.1