Shareholders' Equity - Additional Information (Detail) - $ / shares	6 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Class of Stock [Line Items]
Preferred stock, shares authorized	1,000,000	1,000,000
Preferred stock, par value	$ 1.00	$ 1.00
Warrant [Member] | Assumed In Acquisition [Member]
Class of Stock [Line Items]
Exercise price of each class of warrants or rights outstanding	$ 517.89
Warrant to purchase common stock	95,580
Warrants, date of expiration	Dec. 12, 2018