Convertible Debt and Notes Payable - Convertible Debt (Details) - USD ($)		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Dec. 14, 2017	Mar. 10, 2014
Debt and Capital Lease Obligations [Line Items]
Purchase of treasury stock, cost		$ 18,000,000.0
Convertible debt	[1]	119,929,000		$ 118,688,000
Amortization of debt discount		1,109,000	$ 1,349,000
Convertible Debt
Debt and Capital Lease Obligations [Line Items]
Convertible debt, unamortized discount		13,700,000		$ 14,900,000
2022 convertible note | Convertible Debt
Debt and Capital Lease Obligations [Line Items]
Debt Instrument, Face Amount					$ 135,000,000.0
Debt Instrument, Convertible, Conversion Price					$ 17.375
Purchase of treasury stock, cost		19,500,000
Convertible debt		135,000,000.0
Interest on Convertible Debt, Net of Tax		1,000,000.0	1,000,000.0
Convertible debt, unamortized discount					$ 23,400,000	$ 23,400,000
Amortization of debt discount		$ 1,100,000	1,100,000
Debt Instrument, Interest Rate, Effective Percentage					7.13%
Debt Issuance Costs, Gross					$ 2,200,000
2019 convertible note | Convertible Debt
Debt and Capital Lease Obligations [Line Items]
Debt Instrument, Face Amount						$ 149,500,000
Debt Instrument, Repurchase Amount					$ 115,100,000
Interest on Convertible Debt, Net of Tax			100,000
Amortization of debt discount			$ 300,000
Debt Instrument, Interest Rate, Effective Percentage						8.89%
Interest rate						3.00%

[1] The carrying amount of the convertible debt includes an unamortized discount of $13.7 million and $14.9 million as of March 31, 2020 and December 31, 2019, respectively.