Operating Segments (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2011
Segment Reporting Information [Line Items]
Revenues before reimbursable items	$ 395,179	$ 362,643
Revenue for reportable segment	461,162	429,430
Depreciation and amortization	40,873	41,068
Operating income	84,831	73,028
Change in revenues before reimbursable items	32,536
Change in total revenues	31,732
Change in depreciation and amortization	(195)
Change in operating income	11,803
Percentage of change in revenues before reimbursable items	9.00%
Percentage of change in total revenues	7.40%
Percentage of change in depreciation and amortization	(0.50%)
Percentage of change in operating income	16.20%
Total assets	1,906,135		1,858,392
Change in assets	47,743
Percentage of change in assets	2.60%
North America Services
Segment Reporting Information [Line Items]
Revenues before reimbursable items	204,050	194,590
Revenue for reportable segment	240,599	230,558
Depreciation and amortization	18,454	19,466
Operating income	68,173	55,200
Change in revenues before reimbursable items	9,460
Change in total revenues	10,041
Change in depreciation and amortization	(1,012)
Change in operating income	12,973
Percentage of change in revenues before reimbursable items	4.90%
Percentage of change in total revenues	4.40%
Percentage of change in depreciation and amortization	(5.20%)
Percentage of change in operating income	23.50%
Total assets	1,676,032		1,621,664
Change in assets	54,368
Percentage of change in assets	3.40%
International Services
Segment Reporting Information [Line Items]
Revenues before reimbursable items	96,491	87,419
Revenue for reportable segment	100,360	90,710
Depreciation and amortization	12,911	11,708
Operating income	4,113	11,025
Change in revenues before reimbursable items	9,072
Change in total revenues	9,650
Change in depreciation and amortization	1,203
Change in operating income	(6,912)
Percentage of change in revenues before reimbursable items	10.40%
Percentage of change in total revenues	10.60%
Percentage of change in depreciation and amortization	10.30%
Percentage of change in operating income	(62.70%)
Total assets	439,948		433,203
Change in assets	6,745
Percentage of change in assets	1.60%
Merchant services
Segment Reporting Information [Line Items]
Revenues before reimbursable items	98,356	86,519
Revenue for reportable segment	125,518	115,756
Depreciation and amortization	8,786	9,146
Operating income	34,219	26,923
Change in revenues before reimbursable items	11,837
Change in total revenues	9,762
Change in depreciation and amortization	(360)
Change in operating income	7,296
Percentage of change in revenues before reimbursable items	13.70%
Percentage of change in total revenues	8.40%
Percentage of change in depreciation and amortization	(3.90%)
Percentage of change in operating income	27.10%
Total assets	498,586		487,858
Change in assets	10,728
Percentage of change in assets	2.20%
Intersegment revenues
Segment Reporting Information [Line Items]
Revenues before reimbursable items	(3,718)	(5,885)
Revenue for reportable segment	(5,315)	(7,594)
Change in revenues before reimbursable items	2,167
Change in total revenues	2,279
Percentage of change in revenues before reimbursable items	36.80%
Percentage of change in total revenues	30.00%
Corporate Administration
Segment Reporting Information [Line Items]
Depreciation and amortization	722	748
Operating income	(21,674)	(20,120)
Change in depreciation and amortization	(26)
Change in operating income	(1,554)
Percentage of change in depreciation and amortization	(3.50%)
Percentage of change in operating income	(7.70%)
Total assets	(708,431)		(684,333)
Change in assets	$ (24,098)
Percentage of change in assets	(3.50%)