Stockholders' Equity - Additional Information (Detail) - $ / shares	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2019	Jul. 16, 2019	Dec. 31, 2018
Equity [Abstract]
Authorized capital stock			405,000,000
Common stock, shares authorized		400,000,000	400,000,000	155,000,000
Common stock, par value		$ 0.50	$ 0.50	$ 0.50
Preferred stock, authorized capital stock		5,000,000	5,000,000
Preferred stock, par value			$ 10.00
Common stock warrants exercised, Shares	246,793