SEGMENT INFORMATION (Details) (USD $) In Thousands	3 Months Ended
	Jun. 30, 2011	Jun. 30, 2010
Revenue:
Total revenue	$ 288,934	$ 270,395
Income (loss) from operations:
Income from operations	22,230	22,076
Information services
Revenue:
Total revenue	225,604	210,656
Income (loss) from operations:
Income from operations	20,172	20,879
Information products
Revenue:
Total revenue	63,330	59,739
Income (loss) from operations:
Income from operations	2,302	1,140
Other
Income (loss) from operations:
Income from operations	$ (244)	$ 57