Employer Sponsored Benefit Plans (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Components of net periodic benefit cost
Interest cost	$ 517	$ 509	$ 1,550	$ 1,840
Expected return on assets	(590)	(605)	(1,770)	(2,192)
Amortization of actuarial loss	224	182	673	542
Pension settlement cost	0	4,870	0	4,870
Net periodic benefit cost	$ 151	$ 4,956	$ 453	$ 5,060