Accrued Expenses and Other Liabilities (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Accrued Expenses
Salaries and wages	$ 114,446	$ 106,281
Deferred compensation	3,209	2,505
Pension benefits	3,739	3,660
Other postretirement benefits	2,112	2,414
Other employee benefits	7,172	3,809
Insurance obligations	132,246	125,835
Environmental liabilities	3,877	4,515
Operating taxes	92,330	94,188
Income taxes	5,066	2,623
Interest	32,441	33,654
Deposits, mainly from customers	59,388	55,854
Deferred revenue	11,759	15,123
Acquisition holdbacks	3,817	2,012
Other	48,930	43,864
Total	520,532	496,337
Non-Current Liabilities
Salaries and wages	0	0
Deferred compensation	37,093	31,896
Pension benefits	444,657	292,155
Other postretirement benefits	26,889	28,374
Other employee benefits	19,276	6,712
Insurance obligations	189,431	186,700
Environmental liabilities	8,002	8,548
Operating taxes	0	0
Income taxes	22,843	23,813
Interest	0	0
Deposits, mainly from customers	5,929	6,239
Deferred revenue	0	0
Acquisition holdbacks	2,187	0
Other	30,369	31,868
Total	786,676	616,305
Total
Salaries and wages	114,446	106,281
Deferred compensation	40,302	34,401
Pension benefits	448,396	295,815
Other postretirement benefits	29,001	30,788
Other employee benefits	26,448	10,521
Insurance obligations	321,677	312,535
Environmental liabilities	11,879	13,063
Operating taxes	92,330	94,188
Income taxes	27,909	26,436
Interest	32,441	33,654
Deposits, mainly from customers	65,317	62,093
Deferred revenue	11,759	15,123
Acquisition holdbacks	6,004	2,012
Other	79,299	75,732
Total	$ 1,307,208	$ 1,112,642