Fair Value Option - Additional Information (Detail) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Mar. 14, 2019	Feb. 22, 2019	Feb. 22, 2018	Sep. 30, 2017
Fair Value Option Qualitative Disclosures Related To Election [Line Items]
Long term debt, fair value		$ 49,140		$ 49,140		$ 47,277
Principal outstanding balance	[1],[2]	$ 583,549		$ 583,549		$ 645,721
5.75% Senior Subordinated Notes Due August 2023
Fair Value Option Qualitative Disclosures Related To Election [Line Items]
Percentage of conversion of convertible notes		5.75%	5.75%	5.75%	5.75%		5.75%
Convertible Notes
Fair Value Option Qualitative Disclosures Related To Election [Line Items]
Percentage of conversion of convertible notes										1.50%
Convertible Notes | 5.75% Senior Subordinated Notes Due August 2023
Fair Value Option Qualitative Disclosures Related To Election [Line Items]
Percentage of conversion of convertible notes		5.75%	5.75%	5.75%	5.75%	5.75%		5.75%	5.75%
Long term debt, fair value		$ 49,100		$ 49,100		$ 47,300
Principal outstanding balance		94,400		94,400		$ 94,400
Changes in fair value of convertible notes		$ (300)	$ 11,900	$ 1,900	$ (8,400)

[1] Carrying amounts include aggregate unamortized debt discount and debt issuance costs.

[2] Includes the 5.75% Convertible Notes accounted for under the fair value option. Refer to Note 7.