Stock-Based Compensation and Stock Awards - Performance Unit Awards - Additional Information (Detail) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($) Company $ / shares shares	Dec. 31, 2016 USD ($) $ / shares shares	Dec. 31, 2015 USD ($) shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance Unit compensation expense	$ 5,400	$ 4,600	$ 4,500
Anti-dilutive performance share units (in shares) | shares	21,483	186,112
Performance Unit Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share value based on Monte Carlo simulation (in dollars per share) | $ / shares	$ 54.64	$ 53.46
Percentage of grant share price (as a percentage)	131.70%	110.30%
Number of components companies in the Philadelphia Oil Service Index | Company	15
Total share return period (in years)	3 years
Income tax benefit recognized	$ 762	$ 462	$ 1,100
Unrecognized compensation expense related to share based compensation	$ 10,200
Period of recognition for unrecognized compensation expense related to nonvested stock options (in years)	2 years 2 months 12 days
Anti-dilutive performance share units (in shares) | shares	159,810	64,000	61,000
Minimum | Performance Unit Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Participants earning under the term (as a percentage)	0.00%
Maximum | Performance Unit Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Participants earning under the term (as a percentage)	200.00%