Accrued Expenses and Other Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Accrued Expenses
Salaries and wages	$ 90,913	$ 99,032
Deferred compensation	2,992	2,252
Pension benefits	3,796	3,790
Other postretirement benefits	1,506	1,624
Other employee benefits	29,358	8,956
Insurance obligations	127,470	157,014
Operating taxes	92,150	101,649
Income taxes	4,197	3,378
Interest	27,277	31,218
Deposits, mainly from customers	61,225	61,869
Deferred revenue	14,064	13,038
Other	52,241	59,532
Total	507,189	543,352
Non-Current Liabilities
Salaries and wages	0	0
Deferred compensation	46,541	41,691
Pension benefits	451,940	484,892
Other postretirement benefits	19,459	20,002
Other employee benefits	5,854	9,706
Insurance obligations	234,336	213,256
Operating taxes	0	0
Income taxes	23,174	22,366
Interest	0	0
Deposits, mainly from customers	4,569	5,085
Deferred revenue	0	0
Other	31,692	32,597
Total	817,565	829,595
Total
Salaries and wages	90,913	99,032
Deferred compensation	49,533	43,943
Pension benefits	455,736	488,682
Other postretirement benefits	20,965	21,626
Other employee benefits	35,212	18,662
Insurance obligations	361,806	370,270
Operating taxes	92,150	101,649
Income taxes	27,371	25,744
Interest	27,277	31,218
Deposits, mainly from customers	65,794	66,954
Deferred revenue	14,064	13,038
Other	83,933	92,129
Total	$ 1,324,754	$ 1,372,947