Accrued Expenses and Other Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Accrued Expenses
Salaries and wages	$ 94,846		$ 114,446
Deferred compensation	2,243		3,209
Pension benefits	3,687		3,739
Other postretirement benefits	2,097		2,112
Other employee benefits	7,681		7,172
Insurance obligations	136,394		132,246
Environmental liabilities	3,728		3,877
Operating taxes	106,286		92,330
Income taxes	2,785		5,066
Interest	35,875		33,509
Deposits, mainly from customers	64,059		59,388
Deferred revenue	14,388		11,759
Acquisition holdbacks	6,061		3,817
Other	43,592		41,009
Total	523,722	$ 482,521	513,679	$ 494,395
Non-Current Liabilities
Salaries and wages	0		0
Deferred compensation	41,518		37,093
Pension benefits	457,170		444,657
Other postretirement benefits	25,904		26,889
Other employee benefits	16,910		19,276
Insurance obligations	198,860		189,431
Environmental liabilities	7,152		8,002
Operating taxes	0		0
Income taxes	24,704		22,843
Interest	0		0
Deposits, mainly from customers	5,648		5,929
Deferred revenue	0		0
Acquisition holdbacks	0		2,187
Other	21,549		27,035
Total	799,415	$ 784,948	783,342	$ 614,713
Total
Salaries and wages	94,846		114,446
Deferred compensation	43,761		40,302
Pension benefits	460,857		448,396
Other postretirement benefits	28,001		29,001
Other employee benefits	24,591		26,448
Insurance obligations	335,254		321,677
Environmental liabilities	10,880		11,879
Operating taxes	106,286		92,330
Income taxes	27,489		27,909
Interest	35,875		33,509
Deposits, mainly from customers	69,707		65,317
Deferred revenue	14,388		11,759
Acquisition holdbacks	6,061		6,004
Other	65,141		68,044
Total	$ 1,323,137		$ 1,297,021