Activity of Awarded Deferred Common Stock Units (Detail) - USD ($)	8 Months Ended	12 Months Ended
	Sep. 12, 2016	Dec. 31, 2016
Number of shares
Share-based Compensation Arrangements by Share-based Payment Award, Options, Cancelled	$ 3,083,821
Weighted-Average Grant Date Fair Value
Share-based Compensation Arrangement by Share-by Payment Awards, Options, Weighted Average Price of Shares Canceled	$ 16.05
Deferred Common Stock Units
Number of shares
Balance at beginning of year (in shares)	447,498	447,498
Granted (in shares)		0
Converted (in shares)		0
Share-based Compensation Arrangements by Share-based Payment Award, Options, Cancelled		$ (447,498)
Balance at end of year (in shares)		0
Weighted-Average Grant Date Fair Value
Balance at beginning of year (in dollars per share)	$ 7.75	$ 7.75
Granted (in dollars per share)		0.00
Converted (in dollars per share)		0.00
Share-based Compensation Arrangement by Share-by Payment Awards, Options, Weighted Average Price of Shares Canceled		7.75
Balance at end of year (in dollars per share)		$ 0.00