Russell 2500 Index [Member] Russell 3000 Index [Member] Casey s General Stores Inc [Member] ITT Inc [Member] Coherent Corp [Member] Reinsurance Group of America Inc [Member] EMCOR Group Inc [Member] Lumentum Holdings Inc [Member] Ciena Corp [Member] Cullen Frost Bankers Inc [Member] Comfort Systems U S A Inc [Member] Sandisk Corp [Member] Liabilities in Excess of Other Assets [Member] C000006083 [Member] Class R C000199765 [Member] Class K C000006081 [Member] Investor C C000006079 [Member] Investor A C000006082 [Member] Institutional Real Estate Sector [Member] Healthcare Sector [Member] Financial Services Sector [Member] Energy Sector [Member] Short-Term Investments [Member] Investment Type [Axis] Net Assets Investment Company Portfolio Turnover No Trading Symbol Flag