Selected Quarterly Operating Results (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2012	Mar. 31, 2011	Mar. 31, 2010
Revenues:
Software, hardware and supplies	$ 26,562	$ 35,074	$ 31,860	$ 28,911	$ 31,708	$ 29,675	$ 20,375	$ 24,756	$ 122,407	$ 106,514	$ 89,761
Implementation and training services	8,270	6,555	6,094	5,472	4,946	4,262	4,499	4,308	26,391	18,015	14,376
System sales	34,832	41,629	37,954	34,383	36,654	33,937	24,874	29,064	148,798	124,529	104,137
Maintenance	35,871	36,245	35,214	31,502	29,046	27,908	27,529	25,536	138,832	110,019	89,192
Electronic data interchange services	13,081	12,101	11,985	12,092	10,756	10,360	10,142	9,764	49,259	41,022	35,035
Revenue cycle management and related services	11,402	11,147	11,142	11,881	11,622	11,496	11,175	10,772	45,572	45,065	36,665
Other services	13,808	11,643	11,339	10,584	9,030	8,170	7,737	7,791	47,374	32,728	26,782
Maintenance, EDI, RCM and other services	74,162	71,136	69,680	66,059	60,454	57,934	56,583	53,863	281,037	228,834	187,674
Total revenues	108,994	112,765	107,634	100,442	97,108	91,871	81,457	82,927	429,835	353,363	291,811
Cost of revenue:
Software, hardware and supplies	4,976	4,622	4,187	4,614	3,204	5,667	4,696	6,212	18,399	19,779	12,115
Implementation and training services	6,179	5,994	5,050	4,075	4,868	3,677	3,475	2,990	21,298	15,010	11,983
Total cost of system sales	11,155	10,616	9,237	8,689	8,072	9,344	8,171	9,202	39,697	34,789	24,098
Maintenance	4,844	4,412	3,994	3,854	2,875	3,381	3,238	3,454	17,104	12,948	13,339
Electronic data interchange services	8,606	7,890	7,964	7,962	7,321	6,908	6,773	6,709	32,422	27,711	25,262
Revenue cycle management and related services	8,608	8,405	8,456	8,826	8,733	8,715	8,222	8,145	34,295	33,815	27,715
Other services	8,728	7,011	6,369	5,597	6,165	3,981	3,724	4,349	27,705	18,219	20,393
Total cost of maintenance, EDI, RCM and other services	30,786	27,718	26,783	26,239	25,094	22,985	21,957	22,657	111,526	92,693	86,709
Total cost of revenue	41,941	38,334	36,020	34,928	33,166	32,329	30,128	31,859	151,223	127,482	110,807
Gross profit	67,053	74,431	71,614	65,514	63,942	59,542	51,329	51,068	278,612	225,881	181,004
Operating expenses:
Selling, general and administrative	34,195	33,096	32,169	29,386	29,285	27,958	24,829	26,238	128,846	108,310	86,951
Research and development costs	8,907	8,277	7,358	6,827	5,751	5,358	5,232	5,456	31,369	21,797	16,546
Amortization of acquired intangible assets	653	543	520	482	445	445	445	347	2,198	1,682	1,783
Total operating expenses	43,755	41,916	40,047	36,695	35,481	33,761	30,506	32,041	162,413	131,789	105,280
Income from operations	23,298	32,515	31,567	28,819	28,461	25,781	20,823	19,027	116,199	94,092	75,724
Interest income	35	55	75	82	19	55	129	60	247	263	226
Other income (expense), net	261	(218)	(144)	(38)	2	0	65	(6)	(139)	61	268
Income before provision for income taxes	23,594	32,352	31,498	28,863	28,482	25,836	21,017	19,081	116,307	94,416	76,218
Provision for income taxes	8,521	11,247	11,002	9,880	9,929	8,305	7,587	6,989	40,650	32,810	27,839
Net income	$ 15,073	$ 21,105	$ 20,496	$ 18,983	$ 18,553	$ 17,531	$ 13,430	$ 12,092	$ 75,657	$ 61,606	$ 48,379
Net income per share:
Basic	$ 0.26	$ 0.36	$ 0.35	$ 0.33	$ 0.32	$ 0.30	$ 0.23	$ 0.21	$ 1.29	$ 1.06	$ 0.84
Diluted	$ 0.25	$ 0.36	$ 0.35	$ 0.32	$ 0.32	$ 0.30	$ 0.23	$ 0.21	$ 1.28	$ 1.06	$ 0.84
Weighted-average shares outstanding:
Basic	59,048	58,847	58,511	58,362	58,010	57,956	57,870	57,792	58,729	57,894	57,270
Diluted	59,232	59,128	58,902	58,800	58,404	58,280	58,156	58,114	59,049	58,236	57,592
Dividends declared per common share	$ 0.175	$ 0.175	$ 0.175	$ 0.175	$ 0.175	$ 0.150	$ 0.150	$ 0.150	$ 0.700	$ 0.625	$ 0.600