Debt - (Tables)

12 Months Ended

Dec. 31, 2020

Debt Disclosure [Abstract]

Schedule of Long-term Debt Instruments

The following table presents the carrying amounts and estimated fair values of our 2023 notes and our 2025 notes that are not recorded at fair value on our consolidated balance sheets:

	December 31, 2020		December 31, 2019
Issuance	Net Carrying Amount	Estimated Fair Value	Net Carrying Amount	Estimated Fair Value
2023 notes	$22,482	$59,894	$119,716	$142,672
2025 notes	$488,268	$802,083	$—	$—

The following table summarizes borrowings under these facilities as of the periods presented:

	December 31, 2020						December 31, 2019
Lender	Borrowing Capacity		Outstanding Borrowings		Weighted Average Interest Rate on Outstanding Borrowings		Borrowing Capacity		Outstanding Borrowings		Weighted Average Interest Rate on Outstanding Borrowings
Western Alliance Bank	$	50,000	$	18,277	3.25	%	$	24,500	$	8,489	3.79	%
Texas Capital Bank, N.A.	40,000		12,903		3.35	%	24,500		10,210		3.51	%
Flagstar Bank, FSB	15,000		7,849		3.00	%	$	15,000	$	2,603	3.69	%
Total	$	105,000	$	39,029	—	%	$	64,000	$	21,302	—	%

The following table summarizes borrowings under this facility as of the period presented:

	December 31, 2020						December 31, 2019
Lender	Borrowing Capacity		Outstanding Borrowings		Weighted Average Interest Rate on Outstanding Borrowings		Borrowing Capacity		Outstanding Borrowings		Weighted Average Interest Rate on Outstanding Borrowings
Goldman Sachs Bank USA	$	100,000	$	23,949	4.40	%	$	100,000	$	4,444	4.45	%

Convertible Senior Notes

We have issued convertible senior notes with the following characteristics:

Issuance	Maturity Date	Stated Cash Interest Rate	Effective Interest Rate	First Interest Payment Date	Semi-Annual Interest Payment Dates	Conversion Rate
2023 notes	July 15, 2023	1.75%	7.25%	January 15, 2019	January 15; July 15	32.7332
2025 notes	October 15, 2025	—	6.52%	—	—	13.7920

The components of the convertible senior notes were as follows:

	December 31, 2020
Issuance	Aggregate Principal Amount		Unamortized Debt Discount		Unamortized Debt Issuance Costs		Net Carrying Amount
2023 notes	$	25,626	$	2,776	$	368	$	22,482
2025 notes	661,250		163,077		9,905		488,268

	December 31, 2019
Issuance	Aggregate Principal Amount		Unamortized Debt Discount		Unamortized Debt Issuance Costs		Net Carrying Amount
2023 notes	$	143,750	$	21,231	$	2,803	$	119,716

Interest Income and Interest Expense Disclosure

	Year Ended
	December 31, 2020						December 31, 2019						December 31, 2018
	2023 notes		2025 notes		Total		2023 notes		2025 notes		Total		2023 notes		2025 notes		Total
Contractual interest expense	$	2,113	$	—	$	2,113	$	2,516	$	—	$	2,516	$	1,097	$	—	$	1,097
Amortization of debt discount	4,735		5,693		10,428		5,405		—		5,405		2,280		—		2,280
Amortization of debt issuance costs	623		346		969		724		—		724		304		—		304
Interest expense	$	7,471	$	6,039	$	13,510	$	8,645	$	—	$	8,645	$	3,681	$	—	$	3,681