XML 67 R55.htm IDEA: XBRL DOCUMENT

Benefit Plans - Additional Information (Detail) $ in Millions	6 Months Ended
	Jun. 30, 2017 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Number of highest-paid consecutive years for benefits	5 years
Defined benefit pension plan
Defined Benefit Plan Disclosure [Line Items]
Minimum eligibility for full-time employees, age	21 years
Amount contributed to pension plan, expected in future	$ 2.1
Defined benefit pension plan \| Minimum
Defined Benefit Plan Disclosure [Line Items]
Period of service credit by employee	1 year