Quarterly Financial Data (Tables)

12 Months Ended

Dec. 31, 2011

Quarterly Financial Data [Abstract]

Schedule of Quarterly Financial Information

The following tables set forth selected unaudited quarterly financial data. The quarterly financial data reflects, in the opinion of the Company, all normal and recurring adjustments necessary to present fairly the results of operations for such periods. Results of any one or more quarters are not necessarily indicative of annual results or continuing trends.

	2011
	March 31,			June 30,			September 30,			December 31,
	(in thousands, except per share data)
Revenues	$	700,864		$	752,673		$	734,607		$	681,838
Cost of services	599,767			644,647			629,181			580,084
General and administrative expenses	45,242			48,858			46,918			47,931
Operating income	55,855			59,168			58,508			53,823
Interest expense	(3,970		)	(3,979		)	(3,857		)	(3,985		)
Interest income	64			59			107			102
Other income (expense), net	96			3,820			(20		)	(289		)
Income before provision for income taxes	52,045			59,068			54,738			49,651
Net income	$	31,903		$	36,442		$	34,486		$	30,475
Basic net income per share - Class A common stock	$	0.87		$	0.99		$	0.94		$	0.83
Weighted average shares outstanding - Class A	23,206			23,357			23,513			23,578
Basic net income per share - Class B common stock	$	0.87		$	0.99		$	0.94		$	0.83
Weighted average shares outstanding - Class B	13,275			13,271			13,193			13,193
Diluted net income per share - Class A common stock	$	0.87		$	0.99		$	0.94		$	0.83
Weighted average shares outstanding - Class A	23,357			23,510			23,607			23,643
Diluted net income per share - Class B common stock	$	0.87		$	0.99		$	0.94		$	0.83
Weighted average shares outstanding - Class B	13,275			13,271			13,193			13,193
	2010
	March 31,			June 30,			September 30,			December 31,
	(in thousands, except per share data)
Revenues	$	587,557		$	661,611		$	656,954		$	697,916
Cost of services	499,566			562,306			555,318			591,441
General and administrative expenses	42,759			42,776			47,121			47,611
Operating income	45,232			56,529			54,515			58,864
Interest expense	(997		)	(3,598		)	(3,970		)	(4,002		)
Interest income	128			57			51			125
Other income (expense), net	(62		)	(270		)	64			(215		)
Income before provision for income taxes	44,301			52,718			50,660			54,772
Net income	$	27,541		$	32,167		$	31,376		$	34,012
Basic net income per share - Class A common stock	$	0.76		$	0.89		$	0.86		$	0.94
Weighted average shares outstanding - Class A	22,415			22,872			23,010			23,082
Basic net income per share - Class B common stock	$	0.76		$	0.89		$	0.86		$	0.94
Weighted average shares outstanding - Class B	13,605			13,317			13,276			13,275
Diluted net income per share - Class A common stock	$	0.76		$	0.88		$	0.86		$	0.93
Weighted average shares outstanding - Class A	22,727			23,126			23,171			23,251
Diluted net income per share - Class B common stock	$	0.76		$	0.88		$	0.86		$	0.93
Weighted average shares outstanding - Class B	13,605			13,317			13,276			13,275