Statement of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Cash and cash equivalents, at beginning of period	$ 484,502	$ 429,784
Net income	12,893	14,005
Depreciation and amortization, net of accretion	59,409	55,673
Non-cash compensation and employee benefits	4,761	9,180
Increase in deferred income taxes	1,709	5,556
Provision for uncollectible accounts	439	401
Loss (gain) from sale of property and equipment	(1,211)	249
Receivables	(87,887)	(49,353)
Prepaid expense	(18,051)	(9,307)
Accounts payable	34,843	26,290
Accrued variable compensation	(26,787)	(44,256)
Accrued liabilities, excluding accrued variable compensation and employee benefits	35,301	39,831
Self-insurance accruals	13,546	(1,157)
Accrued income taxes	1,608	(5,483)
Employee benefits	(33,860)	(15,675)
Other	(1,256)	1,393
Net cash provided by (used in) operating activities	(4,543)	27,347
Capital expenditures	(70,478)	(49,686)
Software expenditures	(2,637)	(960)
Proceeds from sales of property and equipment	5,842	1,396
Proceeds from sales of marketable securities	0	3,200
Net cash used in investing activities	(67,273)	(46,050)
Payment of capital leases	(2,866)	(3,173)
Net proceeds from (repayment of) short-term borrowings	286	(4,162)
Proceeds from exercise of stock options	824	5,669
Excess tax benefit from share-based compensation	505	733
Payments of common dividends	(5,703)	(5,617)
Net cash used in financing activities	(6,954)	(6,550)
Decrease in cash and cash equivalents	(78,770)	(25,253)
Cash and Cash Equivalents, at end of period	405,732	404,531
Cash paid for income taxes, net	2,554	1,897
Cash paid for interest	15,735	15,929
Property, plant and equipment acquired through partial non-monetary exchanges	2,518	6,394
Property, plant and equipment acquired through capital leases	$ 3,810	$ 0