Face (par) amount of debt instrument at time of issuance.

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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Debt - Summary of Debt Obligations (Details) - USD ($)	Sep. 30, 2020	Aug. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Long-term debt, carrying value	$ 1,242,700,000		$ 832,700,000
Federal Home Loan Bank Advances (FHLB)
Debt Instrument [Line Items]
Long-term debt, carrying value	$ 155,000,000.0		155,000,000.0
Stated interest rate	1.91%
Senior Notes \| 5.75% Senior Notes Due 2023
Debt Instrument [Line Items]
Long-term debt, carrying value	$ 240,400,000		420,800,000
Stated interest rate	5.75%	5.75%
Debt instrument, face amount	$ 242,300,000
Senior Notes \| 5.25% Senior Notes Due 2028
Debt Instrument [Line Items]
Long-term debt, carrying value	$ 638,500,000		0
Stated interest rate	5.25%	5.25%
Debt instrument, face amount	$ 650,000,000	$ 650,000,000
9% Convertible Junior Subordinated Debentures
Debt Instrument [Line Items]
Long-term debt, carrying value	$ 208,800,000		$ 256,900,000
Stated interest rate	9.00%