Western Asset Oregon Municipals Fund S000016636 [Member] Bloomberg Municipal Bond Index (reflects no deduction for fees, expenses or taxes) Bloomberg Municipal Bond Index [Member] Bloomberg Oregon Municipal Bond Index (reflects no deduction for fees, expenses or taxes) Bloomberg Oregon Municipal Bond Index [Member] Class A C000046459 [Member] Class B C000046460 [Member] Class C C000046461 [Member] Class I C000046462 [Member] Class FI C000066859 [Member] Class IS C000195075 [Member] Market events risk [Member] Inflation risk [Member] Credit risk [Member] Risks relating to investments in municipal securities [Member] Risks associated with focusing on investments in Oregon municipal securities [Member] High yield junk bonds risk [Member] Derivatives risks [Member] Leverage risk [Member] Tender option bond risk [Member] Illiquidity risk [Member] Tax risk [Member] Prepayment or call risk [Member] Extension risk [Member] Investing in ETFs risk [Member] Valuation risk [Member] Portfolio management risk [Member] Redemption risk [Member] Cybersecurity risk [Member] Market and interest rate risk [Member]