Consolidated Statements Of Income (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Consolidated Statements Of Income
Revenues	$ 211,507,000	$ 192,954,000	$ 419,897,000	$ 376,755,000
Operating costs and expenses:
Costs of services provided	181,742,000	165,240,000	361,727,000	323,812,000
Selling, general and administrative	15,511,000	13,150,000	32,291,000	27,051,000
Other income/(loss):
Investment and interest	463,000	(383,000)	1,177,000	366,000
Income before income taxes	14,717,000	14,181,000	27,056,000	26,258,000
Income taxes	4,889,000	5,460,000	9,461,000	10,109,000
Net income	$ 9,828,000	$ 8,721,000	$ 17,595,000	$ 16,149,000
Basic earnings per common share	$ 0.15	$ 0.13	$ 0.26	$ 0.25
Diluted earnings per common share	$ 0.15	$ 0.13	$ 0.26	$ 0.24
Cash dividends per common share	$ 0.15750	$ 0.15	$ 0.31	$ 0.29
Weighted average number of common shares outstanding
Basic	66,517,000	65,948,000	66,459,000	65,898,000
Diluted	67,545,000	66,978,000	67,499,000	66,983,000