Components of net periodic pension cost (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Amortization of prior service credit	$ (950)	$ 0
Recognized net actuarial losses	2,126	6,169
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan Interest Cost	7,461	6,966
Expected return on plan assets	(11,630)	(10,804)
Defined Benefit Plan Amortization Of Net Gains Losses	2,018	5,363
Total net periodic pension cost	(2,151)	1,525
Other Pension Plans Defined Benefit Member
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan Interest Cost	415	373
Expected return on plan assets	(606)	(542)
Defined Benefit Plan Amortization Of Net Gains Losses	108	333
Total net periodic pension cost	$ (83)	$ 164