Consolidated Statements of Comprehensive Income (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Statement Of Income And Comprehensive Income [Abstract]
Revenue	$ 168,839	$ 149,841	$ 542,784	$ 491,603
Operating expenses	150,935	137,204	462,560	422,783
Gross margin	17,904	12,637	80,224	68,820
Corporate general and administrative expenses	8,944	7,475	26,577	25,594
Operating income	8,960	5,162	53,647	43,226
Other income (expense):
Interest expense	(3,815)	(3,576)	(12,016)	(11,198)
Gain on sale of operations, net	6	21	72	2,660
Other income, net	2,371	2,541	4,614	5,022
Total other expense, net	(1,438)	(1,014)	(7,330)	(3,516)
Income from continuing operations before income tax expense	7,522	4,148	46,317	39,710
Income tax expense	2,441	1,066	18,882	15,681
Income from continuing operations after income tax expense	5,081	3,082	27,435	24,029
Income from discontinued operations, net of tax	964	2,193	4,132	5,839
Gain on disposal of discontinued operations, net of tax	56,315	32	58,243	72
Net income	62,360	5,307	89,810	29,940
Basic:
Continuing operations	$ 0.10	$ 0.06	$ 0.56	$ 0.49
Discontinued operations	$ 1.18	$ 0.05	$ 1.27	$ 0.12
Net income	$ 1.28	$ 0.11	$ 1.83	$ 0.61
Diluted:
Continuing operations	$ 0.10	$ 0.06	$ 0.55	$ 0.49
Discontinued operations	$ 1.17	$ 0.05	$ 1.26	$ 0.12
Net income	$ 1.27	$ 0.11	$ 1.81	$ 0.61
Basic weighted average shares outstanding	48,504	48,895	49,187	49,014
Diluted weighted average shares outstanding	49,003	49,109	49,537	49,278
Comprehensive Income:
Net income	62,360	5,307	89,810	29,940
Other comprehensive income, net of tax	65	53	2	50
Comprehensive income	$ 62,425	$ 5,360	$ 89,812	$ 29,990