Earnings Per Share - Additional Information (Detail) - shares shares in Millions	3 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Mar. 14, 2019	Dec. 31, 2018	Feb. 22, 2018	Sep. 30, 2017
Earnings Per Share Disclosure [Line Items]
Anti-dilutive shares	0.4	0.2
Percentage of conversion of convertible notes		5.75%
5.75% Senior Subordinated Notes Due August 2023
Earnings Per Share Disclosure [Line Items]
Percentage of conversion of convertible notes	5.75%	5.75%	5.75%
Convertible Notes
Earnings Per Share Disclosure [Line Items]
Percentage of conversion of convertible notes						1.50%
Convertible Notes | 5.75% Senior Subordinated Notes Due August 2023
Earnings Per Share Disclosure [Line Items]
Percentage of conversion of convertible notes	5.75%	5.75%		5.75%	5.75%
Performance Shares
Earnings Per Share Disclosure [Line Items]
Anti-dilutive shares	0.4	0.1