Segment Information - Information about Company's Segment Data (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Segment Reporting Information [Line Items]
External revenue	$ 130,538	$ 123,407	$ 250,743	$ 237,077
Cost of revenue (exclusive of depreciation and amortization)	89,871	84,253	172,951	166,135
Depreciation and amortization including acquisition-related intangible assets	2,702	2,675	5,349	5,303
Other operating expenses	25,065	23,802	49,583	47,757
Segment contribution	12,900	12,677	22,860	17,882
Interest expense and other unallocated items	(8,044)	(8,439)	(15,674)	(16,022)
Income before income taxes	4,856	4,238	7,186	1,860
Provision for income taxes	1,066	771	1,514	1,363
Net income (loss)	3,790	3,467	5,672	497
GLC [Member]
Segment Reporting Information [Line Items]
External revenue	87,651	80,275	169,067	152,828
Cost of revenue (exclusive of depreciation and amortization)	58,665	54,164	113,387	106,485
Depreciation and amortization including acquisition-related intangible assets	1,290	1,296	2,552	2,599
Other operating expenses	19,261	18,655	38,240	37,669
Segment contribution	8,435	6,160	14,888	6,075
Income before income taxes	8,435	6,160	14,888	6,075
Net income (loss)	8,435	6,160	14,888	6,075
GES [Member]
Segment Reporting Information [Line Items]
External revenue	36,689	37,081	69,961	72,359
Cost of revenue (exclusive of depreciation and amortization)	26,004	25,247	49,663	49,924
Depreciation and amortization including acquisition-related intangible assets	801	770	1,599	1,526
Other operating expenses	5,380	4,702	10,494	9,098
Segment contribution	4,504	6,362	8,205	11,811
Income before income taxes	4,504	6,362	8,205	11,811
Net income (loss)	4,504	6,362	8,205	11,811
Interpretation [Member]
Segment Reporting Information [Line Items]
External revenue	6,198	6,051	11,715	11,890
Cost of revenue (exclusive of depreciation and amortization)	5,202	4,842	9,901	9,726
Depreciation and amortization including acquisition-related intangible assets	10	8	18	16
Other operating expenses	424	445	849	990
Segment contribution	562	756	947	1,158
Income before income taxes	562	756	947	1,158
Net income (loss)	562	756	947	1,158
Corporate and Other [Member]
Segment Reporting Information [Line Items]
Depreciation and amortization including acquisition-related intangible assets	601	601	1,180	1,162
Segment contribution	(601)	(601)	(1,180)	(1,162)
Interest expense and other unallocated items	(8,044)	(8,439)	(15,674)	(16,022)
Income before income taxes	(8,645)	(9,040)	(16,854)	(17,184)
Provision for income taxes	1,066	771	1,514	1,363
Net income (loss)	$ (9,711)	$ (9,811)	$ (18,368)	$ (18,547)