Income Taxes - Net Deferred Tax Liability (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Components Of Deferred Tax Assets And Liabilities [Abstract]
Deferred revenue	$ 7,982	$ 7,362
Employee benefits	89,986	87,960
Bad debt reserves	5,990	7,421
Loss reserves	934	1,793
Pension	26,383	18,817
Net operating loss carryforward	14,067	13,290
Securities	0	11,356
Foreign tax credit	6,724	8,415
Operating lease liabilities	72,119	0
Other	2,116	5,464
Deferred tax assets before valuation allowance	226,301	161,878
Valuation allowance	(9,846)	(10,621)
Deferred tax assets	216,455	151,257
Depreciable and amortizable assets	241,799	230,758
Claims and related salvage	104,004	108,497
Investments in affiliates	612	1,957
Securities	39,035	0
Operating lease assets	65,121	0
Unremitted foreign earnings	13,709	10,506
Deferred tax liabilities	464,280	351,718
Net deferred tax liability	$ 247,825	$ 200,461