3.26.1 html 956 44 1 true 152 0 false 3 false false R1.htm 030000 - Disclosure - Form N-CSR Cover Sheet http://xbrl.sec.gov/oef/role/NcsrCover Form N-CSR Cover Cover 1 false false R2.htm 030001 - Disclosure - Shareholder Report Sheet http://xbrl.sec.gov/oef/role/ShareholderReport Shareholder Report Notes 2 false false R3.htm 040010 - Disclosure - Shareholder Report, Line Graph (Details) Sheet http://xbrl.sec.gov/oef/role/ShareholderReportLineGraphDetails Shareholder Report, Line Graph (Details) Details 3 false false R4.htm 040015 - Disclosure - Shareholder Report, Average Annual Return (Details) Sheet http://xbrl.sec.gov/oef/role/ShareholderReportAverageAnnualReturnDetails Shareholder Report, Average Annual Return (Details) Details 4 false false R5.htm 040020 - Disclosure - Shareholder Report, Holdings (Details) Sheet http://xbrl.sec.gov/oef/role/ShareholderReportHoldingsDetails Shareholder Report, Holdings (Details) Details 5 false false All Reports Book All Reports cik0001100663-20260522.xsd d341043dncsr.htm g341043chartimages_11648928.jpg g341043chartimages_11648973.jpg g341043chartimages_11649018.jpg g341043chartimages_11649063.jpg g341043chartimages_11649108.jpg g341043chartimages_11649153.jpg g341043chartimages_11649198.jpg g341043chartimages_11649243.jpg g341043chartimages_11649288.jpg g341043chartimages_11649333.jpg g341043chartimages_11649378.jpg g341043chartimages_11649423.jpg g341043chartimages_11649468.jpg g341043chartimages_11649513.jpg g341043chartimages_11649558.jpg g341043chartimages_11649603.jpg g341043chartimages_11649648.jpg g341043chartimages_11649693.jpg g341043chartimages_11649738.jpg g341043chartimages_11649783.jpg g341043images_30957.jpg g341043images_30959.jpg g341043img004fe2c23.jpg g341043img23c374c32.jpg g341043img2444ca6f1.jpg g341043img350203a61.jpg g341043img3baafa252.jpg g341043img3c65e75b3.jpg g341043img591205632.jpg g341043img5fd94def2.jpg g341043img66eb48702.jpg g341043img7bc445e93.jpg g341043img901097f51.jpg g341043img9abdf5a33.jpg g341043img9c295c152.jpg g341043imga2c818553.jpg g341043imgb2560e9a2.jpg g341043imgcbf333403.jpg g341043imgcf550b863.jpg g341043imgd83f3d231.jpg g341043imgdfd7b0473.jpg g341043imge8035b762.jpg g341043imge881fc901.jpg g341043imgf05378541.jpg g341043imgfc73c0761.jpg g341043imgfe5522991.jpg http://fasb.org/us-gaap/2025 http://xbrl.sec.gov/dei/2025 http://xbrl.sec.gov/oef/2025 false false