Estimated Fair Values of Other Financial Instruments (Parenthetical) (Detail)	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Mar. 14, 2019	Feb. 22, 2019	Feb. 22, 2018	Sep. 30, 2017
5.75% Senior Subordinated Notes Due August 2023
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Percentage of conversion of convertible notes	5.75%		5.75%	5.75%
Convertible Notes
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Percentage of conversion of convertible notes							1.50%
Convertible Notes | 5.75% Senior Subordinated Notes Due August 2023
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Percentage of conversion of convertible notes	5.75%	5.75%	5.75%		5.75%	5.75%