Business Segments (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Segment Reporting Information [Line Items]
Revenue	$ 117,220	$ 113,197	$ 104,899	$ 101,373	$ 105,985	$ 99,671	$ 102,311	$ 93,605	$ 436,689	$ 401,572	$ 333,167
Gain on reversal of deferred rent liability									0	0	1,041
Gain (loss) on change in fair value of contingent consideration, net									1,676	(789)	517
Operating income									38,352	35,682	27,943
Interest expense									(366)	(269)	(209)
Other income									502	389	657
Income before income tax expense									38,488	35,802	28,391
Learning Solutions [Member]
Segment Reporting Information [Line Items]
Revenue									189,899	158,118	126,177
Operating income									15,210	15,927	8,938
Professional and Technical Services [Member]
Segment Reporting Information [Line Items]
Revenue									72,577	82,447	83,551
Operating income									5,810	6,868	8,390
Sandy Training and Marketing [Member]
Segment Reporting Information [Line Items]
Revenue									70,699	70,243	54,604
Operating income									4,672	4,897	3,018
Performance Readiness Solutions [Member]
Segment Reporting Information [Line Items]
Revenue									53,882	55,794	40,079
Operating income									2,688	2,548	601
Energy Services [Member]
Segment Reporting Information [Line Items]
Revenue									49,632	34,970	28,756
Operating income									$ 8,296	$ 6,231	$ 5,438