Debt Obligations - Convertible Senior Unsecured Notes (Details)	1 Months Ended		3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2022 USD ($) $ / shares	Aug. 31, 2022 USD ($) $ / shares	Sep. 30, 2022 USD ($) $ / shares	Sep. 30, 2021 USD ($)	Sep. 30, 2022 USD ($) $ / shares	Sep. 30, 2021 USD ($)	Dec. 31, 2021 USD ($)	Oct. 31, 2021
Debt Obligations
Accrued interest and repurchase premiums		$ 5,200,000
Notes settled with cash						$ 14,300,000
Loss on extinguishment of debt			$ (3,262,000)		$ (4,612,000)	(1,370,000)
Total	$ 14,455,934,000		14,455,934,000		14,455,934,000
Convertible Senior Unsecured Notes
Debt Obligations
Junior subordinated notes	353,608,000		353,608,000		$ 353,608,000		$ 264,000,000
Percentage of the Notes required to be repurchased if the agreement is fundamentally changed					100.00%
Unamortized Debt Discount							2,520,000
Unamortized Deferred Financing Fees	7,568,000		7,568,000		$ 7,568,000		2,095,000
Total	$ 346,040,000		346,040,000		346,040,000		259,385,000
Net Carrying Value, Equity Component							$ 8,684,000
Interest expense			5,800,000	$ 4,500,000	13,400,000	14,100,000
Interest expense related to cash coupon			5,000,000.0	3,100,000	11,300,000	9,700,000
Debt discount				800,000	$ 2,100,000	2,000,000.0
Deferred fees expensed as interest expense			$ 800,000	$ 600,000		$ 2,400,000
Cost of the notes (as a percent)	7.92%		7.92%		7.92%		6.71%
Cost of the notes excluding the amortization of the debt discount (as a percent)							5.73%
7.50% convertible notes
Debt Obligations
Junior subordinated notes		$ 287,500,000
Interest rate (as a percent)	7.50%	7.50%	7.50%		7.50%
Proceeds received, net of estimated issuance costs		$ 279,300,000
Conversion rate of the notes to common stock, per $1,000 principal amount of notes	59.8480	59.8480
Conversion price per share of common stock | $ / shares	$ 16.71	$ 16.71	$ 16.71		$ 16.71
7.50% convertible notes | First Offering
Debt Obligations
Junior subordinated notes		$ 1,000
4.75% Convertible Notes
Debt Obligations
Junior subordinated notes	$ 66,100,000		$ 66,100,000		$ 66,100,000
Interest rate (as a percent)	4.75%	4.75%	4.75%		4.75%
Cash paid for the exchange of convertible notes		$ 203,100,000
Senior Notes
Debt Obligations
Junior subordinated notes	$ 1,295,750,000		$ 1,295,750,000		$ 1,295,750,000		$ 1,295,750,000
Unamortized Deferred Financing Fees	12,200,000		12,200,000		12,200,000		15,200,000
8.00% Convertible Notes
Debt Obligations
Junior subordinated notes	$ 70,750,000		$ 70,750,000		$ 70,750,000		70,750,000
Interest rate (as a percent)	8.00%		8.00%		8.00%
4.50% Convertible Notes
Debt Obligations
Junior subordinated notes	$ 270,000,000		$ 270,000,000		$ 270,000,000		270,000,000
Interest rate (as a percent)	4.50%		4.50%		4.50%
5.75% Convertible Notes
Debt Obligations
Junior subordinated notes	$ 90,000,000		$ 90,000,000		$ 90,000,000		90,000,000
Interest rate (as a percent)	5.75%		5.75%		5.75%
5.625% Notes
Debt Obligations
Junior subordinated notes	$ 125,000,000		$ 125,000,000		$ 125,000,000		125,000,000
Interest rate (as a percent)	5.625%		5.625%		5.625%			5.625%
5.00% Convertible Notes
Debt Obligations
Junior subordinated notes	$ 175,000,000		$ 175,000,000		$ 175,000,000		175,000,000
Interest rate (as a percent)	5.00%		5.00%		5.00%
Junior subordinated notes
Debt Obligations
Junior subordinated notes	$ 154,336,000		$ 154,336,000		$ 154,336,000		154,336,000
Deferred fees expensed as interest expense					$ 1,600,000		$ 1,700,000