Pension and Employee Benefit Plans - Components of Pension and Employee Benefit Expenses (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Pension plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 50	$ 17	$ 100	$ 34
Interest cost	357	78	715	156
Expected return on plan assets	(488)	(102)	(976)	(204)
Amortization of net actuarial loss	44	92	88	184
Net periodic benefit cost (gain)	(37)	85	(73)	170
Health care plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	1	1	3	2
Amortization of gain	(1)	(4)	(3)	(8)
Net periodic benefit cost (gain)	$ 0	$ (3)	$ 0	$ (6)