Accrued Expenses and Other Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Accrued Expenses
Salaries and wages	$ 99,032	$ 114,446
Deferred compensation	2,252	3,209
Pension benefits	3,790	3,739
Other postretirement benefits	1,624	2,112
Other employee benefits	8,956	7,172
Insurance obligations	157,014	132,246
Environmental liabilities	3,791	3,877
Operating taxes	101,649	92,330
Income taxes	3,378	5,066
Interest	31,218	33,509
Deposits, mainly from customers	61,869	59,388
Deferred revenue	13,038	11,759
Acquisition holdbacks	2,081	3,817
Other	53,660	41,009
Total	543,352	513,679
Non-Current Liabilities
Salaries and wages	0	0
Deferred compensation	41,691	37,093
Pension benefits	484,892	444,657
Other postretirement benefits	20,002	26,889
Other employee benefits	9,706	19,276
Insurance obligations	213,256	189,431
Environmental liabilities	6,554	8,002
Operating taxes	0	0
Income taxes	22,366	22,843
Interest	0	0
Deposits, mainly from customers	5,085	5,929
Deferred revenue	0	0
Acquisition holdbacks	0	2,187
Other	26,043	27,035
Total	829,595	783,342
Total
Salaries and wages	99,032	114,446
Deferred compensation	43,943	40,302
Pension benefits	488,682	448,396
Other postretirement benefits	21,626	29,001
Other employee benefits	18,662	26,448
Insurance obligations	370,270	321,677
Environmental liabilities	10,345	11,879
Operating taxes	101,649	92,330
Income taxes	25,744	27,909
Interest	31,218	33,509
Deposits, mainly from customers	66,954	65,317
Deferred revenue	13,038	11,759
Acquisition holdbacks	2,081	6,004
Other	79,703	68,044
Total	$ 1,372,947	$ 1,297,021