Summary of Nonvested Stock Option Transactions (Detail) shares in Thousands	12 Months Ended
	Dec. 31, 2016 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options, Nonvested at December 31, 2015 | shares	51
Number of options, Granted | shares	0
Number of options, Cancelled | shares	0
Number of options, Vested | shares	(51)
Number of options, Nonvested at December 31, 2016 | shares	0
Weighted average grant date fair value, Nonvested at December 31, 2015 | $ / shares	$ 6.50
Weighted average grant date fair value, Granted | $ / shares	0
Weighted average grant date fair value, Cancelled | $ / shares	0
Weighted average grant date fair value, Vested | $ / shares	6.50
Weighted average grant date fair value, Nonvested at December 31, 2016 | $ / shares	$ 0