Employee Benefit Plans (Detail) - Net Periodic Benefit Pension Expense (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Components of net periodic benefit cost:
Service cost	$ 0	$ 2,600	$ 2,862
Interest cost	2,346	2,414	2,720
Expected return on plan assets	(4,931)	(4,299)	(4,456)
Recognized net actuarial loss	249	1,453	1,684
Amortization of prior service cost	0	1	3
Recognized settlement loss	1,377	0	0
Net periodic (income) cost	(959)	2,169	2,813
Other changes in plan assets and benefit obligations recognized as a charge to other comprehensive income (loss):
Amortization of prior service cost	0	1	4
Amortization of net loss	1,625	1,453	1,683
Total unrealized (loss) gain	(9,127)	17,600	(6,520)
Total recognized in net periodic pension cost and other comprehensive income (loss)	(8,168)	15,431	(9,333)
Weighted-average assumptions used to determine the net periodic cost:
Discount rate	4.30%	3.40%	4.40%
Expected return on plan assets	7.25%	7.25%	7.25%
Change In Plan
Other changes in plan assets and benefit obligations recognized as a charge to other comprehensive income (loss):
Net (loss) gain for the period	$ (10,752)	$ 16,146	$ (8,207)
Periodic Cost
Weighted-average assumptions used to determine the net periodic cost:
Rate of compensation increase		2.50%	2.50%