Benefit Plans - Components of Pension Benefit Cost (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2015
Defined Benefit Plan Net Periodic Benefit Cost [Abstract]
Interest cost	$ 62	$ 126
Expected return on plan assets	(82)	(164)
Amortization of net loss	25	43
Settlement costs	96	96
Net periodic benefit cost	$ 101	$ 101