BLACKROCK NATURAL RESOURCES TRUST S000002176 [Member] MSCI All Country World Index (Net) (Reflects no deduction for fees, expenses or taxes except as noted) MSCI All Country World Index Net [Member] S&P Global Natural Resources Index (Net) (Reflects no deduction for fees, expenses or taxes except as noted) S And P Global Natural Resources Index Net [Member] Investor A C000005583 [Member] Investor B C000005584 [Member] Investor C C000005585 [Member] Institutional C000005586 [Member] Natural Resource Related Securities Risk [Member] Commodities Market Risk [Member] Agricultural Production Industry Risk [Member] Asset Based Securities Risk [Member] Chemicals Industry Risk [Member] Convertible Securities Risk [Member] Derivatives Risks [Member] Emerging Markets Risk [Member] Energy Sector Risk [Member] Foreign Securities Risk [Member] Investment Style Risk [Member] Leverage Risk [Member] Market Risk and Selection Risk [Member] Metals and Mining Industry Risk [Member] Mid Cap Securities Risk [Member] Operational and Technology Risks [Member] Precious Metal and Related Securities Risk [Member] Preferred Securities Risk [Member] Rights Risk [Member] Risk of Investing in the United States [Member] Sector Risk [Member] Equity Securities Risk [Member]