Income Taxes (Details3) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Deferred income tax assets-
Accounts receivable and allowance for doubtful accounts	$ 2,293	$ 1,692
Goodwill		4,519
Stock compensation	2,444	2,583
Accrued liabilities and expenses	19,661	20,809
State net operating loss carryforwards	4,668	4,604
Other	1,224	1,186
Total deferred income tax assets	30,290	35,393
Deferred income tax liabilities-
Property and equipment	(5,357)	(5,828)
Long-term contracts	(306)	(237)
Goodwill	(1,124)
Intangible assets	(3,932)	(4,762)
Tax accounting method change (Section 481 adjustments)		(2,978)
Other	(1,131)	(671)
Total deferred income tax liabilities	(11,850)	(14,476)
Less-Valuation allowance	(4,453)	(3,999)
Net deferred income tax assets	13,987	16,918
Deferred income tax assets-
Prepaid expenses and other	19,952	19,294
Other noncurrent assets	2,324	2,594
Total deferred income tax assets	22,276	21,888
Deferred income tax liabilities-
Other current liabilities	335	328
Deferred income tax liabilities	7,954	4,642
Total deferred income tax liabilities	$ 8,289	$ 4,970