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Debt - Principal Terms of Senior and Junior Subordinated Notes (Details) | 12 Months Ended
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Dec. 31, 2019 USD ($)
Senior notes | 2024 Senior Notes |  |
Debt Instrument [Line Items] |  |
Par value (in millions) | $ 400,000,000.0 | [1]
Stated coupon | 4.25% | [1]
Redemption price percentage | 100.00% |
Senior notes | 2024 Senior Notes | Treasury Rate |  |
Debt Instrument [Line Items] |  |
Applicable basis spread over redemption price percentage | 0.25% |
Senior notes | 2025 Senior Notes |  |
Debt Instrument [Line Items] |  |
Par value (in millions) | $ 350,000,000.0 | [1]
Stated coupon | 3.50% | [1]
Redemption price percentage | 100.00% |
Senior notes | 2025 Senior Notes | Treasury Rate |  |
Debt Instrument [Line Items] |  |
Applicable basis spread over redemption price percentage | 0.25% |
Junior subordinated notes |  |
Debt Instrument [Line Items] |  |
Par value (in millions) | $ 300,000,000.0 | [2],[3]
Stated coupon | 5.875% | [2],[3]
Junior subordinated notes | On or after March 30. 2024 |  |
Debt Instrument [Line Items] |  |
Redemption price percentage | 100.00% |
Junior subordinated notes | If changes in tax laws and interpretations occur |  |
Debt Instrument [Line Items] |  |
Redemption price percentage | 100.00% |
Junior subordinated notes | If a rating agency makes certain changes relating to the equity credit criteria for securities |  |
Debt Instrument [Line Items] |  |
Redemption price percentage | 102.00% |
[1] | f 100% of the principal amount of the notes to be redeemed and the remaining principal and interest payments on the notes being redeemed (excluding accrued but unpaid interest to, but not including, the redemption date) discounted to their present value as of the redemption date at the applicable treasury rate plus 0.25%
[2] | The Company may, at its option, and subject to certain conditions and restrictions, defer interest payments subject to the terms of the junior subordinated notes.
[3] | The junior subordinated notes may be redeemed at any time, in whole or in part, on or after March 30, 2024, at 100% of the principal amount of the notes being redeemed plus any accrued and unpaid interest thereon. Prior to March 30, 2024, the junior subordinated notes may also be redeemed, in whole but not in part, at 100% of the principal amount, plus any accrued and unpaid interest, if certain changes in tax laws, regulations or interpretations occur; or at 102% of the principal amount, plus any accrued and unpaid interest, if a rating agency makes certain changes relating to the equity credit criteria for securities with features similar to the junior subordinated notes.

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