CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Operating Activities:
Net income	$ 68,366	$ 61,006	$ 67,394
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation and amortization expense	41,479	37,339	32,739
Deferred income taxes	22,843	26,886	18,788
Stock-based compensation	7,722	6,402	6,222
Amortization of debt costs	570	6,751	6,590
Debt extinguishment expense	0	10,261	0
Other	3,598	(1,876)	(1,703)
Changes in assets and liabilities
Receivables	(84,296)	(165,670)	(6,969)
Inventories	(425)	3,084	(8,118)
Other assets	9,070	30,609	(37,346)
Accounts payable and accrued expenses	24,818	20,260	(14,915)
Deferred revenue and customer advances	(40,848)	(42,872)	(7,212)
Other liabilities	(282)	154	9,666
Net cash provided by (used in) operating activities	52,615	(7,666)	65,136
Investing Activities:
Capital expenditures	(35,655)	(52,175)	(59,815)
Proceeds from sale of investments	12,836	0	0
Purchase price adjustment	4,000	0	0
Proceeds from disposition of property	0	25,589	0
Net cash provided by (used in) investing activities	(18,819)	(26,586)	(59,815)
Financing Activities:
Net proceeds from issuance of common stock	4,824	3,507	2,891
Tax benefit of stock-based compensation	2,393	495	1,676
Repayment of long-term debt	(7,500)	(145,179)	0
Proceeds from issuance of long-term debt	0	150,000	0
Debt issuance costs	0	(1,466)	(3,084)
Net cash provided by (used in) financing activities	(283)	7,357	1,483
Net increase (decrease) in cash and cash equivalents	33,513	(26,895)	6,804
Cash and cash equivalents, beginning of year	232,324	259,219	252,415
Cash and cash equivalents, end of year	$ 265,837	$ 232,324	$ 259,219