Shareholder Report, Line Graph (Details) - USD ($) |
May 31, 2025 |
Feb. 28, 2025 |
Nov. 30, 2024 |
Aug. 31, 2024 |
May 31, 2024 |
Feb. 29, 2024 |
Nov. 30, 2023 |
Aug. 31, 2023 |
May 31, 2023 |
Feb. 28, 2023 |
Nov. 30, 2022 |
Aug. 31, 2022 |
May 31, 2022 |
Feb. 28, 2022 |
Nov. 30, 2021 |
Aug. 31, 2021 |
May 31, 2021 |
Feb. 28, 2021 |
Nov. 30, 2020 |
Aug. 31, 2020 |
May 31, 2020 |
Mar. 16, 2020 |
Feb. 29, 2020 |
Nov. 30, 2019 |
Aug. 31, 2019 |
May 31, 2019 |
Feb. 28, 2019 |
Nov. 30, 2018 |
Aug. 31, 2018 |
May 31, 2018 |
Feb. 28, 2018 |
Nov. 30, 2017 |
Aug. 31, 2017 |
May 31, 2017 |
Feb. 28, 2017 |
Nov. 30, 2016 |
Aug. 31, 2016 |
May 31, 2016 |
Feb. 29, 2016 |
Nov. 30, 2015 |
Sep. 29, 2015 |
Aug. 31, 2015 |
May 31, 2015 |
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| C000036131 | |||||||||||||||||||||||||||||||||||||||||||
| Account Value [Line Items] | |||||||||||||||||||||||||||||||||||||||||||
| Account Value | $ 12,608 | $ 12,434 | $ 12,207 | $ 12,122 | $ 11,854 | $ 11,691 | $ 11,556 | $ 11,447 | $ 11,447 | $ 11,375 | $ 11,402 | $ 11,657 | $ 11,886 | $ 12,022 | $ 11,950 | $ 11,885 | $ 11,711 | $ 11,451 | $ 11,212 | $ 11,166 | $ 10,789 | $ 10,832 | $ 10,641 | $ 10,641 | $ 10,512 | $ 10,297 | $ 10,171 | $ 10,255 | $ 10,200 | $ 10,130 | $ 10,150 | $ 10,171 | $ 10,150 | $ 10,150 | $ 10,080 | $ 10,080 | $ 10,020 | $ 9,920 | $ 9,900 | $ 9,920 | $ 10,000 | ||
| C000161061 | |||||||||||||||||||||||||||||||||||||||||||
| Account Value [Line Items] | |||||||||||||||||||||||||||||||||||||||||||
| Account Value | 645,847 | 637,944 | 624,581 | 620,127 | 606,201 | 597,697 | 590,515 | 584,841 | 584,841 | 579,864 | 581,277 | 593,622 | 603,996 | 610,912 | 607,684 | 603,289 | 595,596 | 581,311 | 569,255 | 566,758 | 546,405 | 549,456 | 538,563 | 539,452 | 532,765 | 520,679 | 514,153 | 518,229 | 515,246 | 512,592 | 512,609 | 513,626 | 512,609 | 512,609 | 508,048 | 508,048 | 505,030 | 500,000 | 498,994 | $ 500,000 | |||
| C000219321 | |||||||||||||||||||||||||||||||||||||||||||
| Account Value [Line Items] | |||||||||||||||||||||||||||||||||||||||||||
| Account Value | 12,278 | 12,093 | 11,855 | 11,763 | 11,495 | 11,330 | 11,161 | 11,045 | 11,045 | 10,951 | 10,977 | 11,194 | 11,390 | 11,499 | 11,439 | 11,356 | 11,190 | 10,921 | 10,693 | 10,641 | 10,250 | $ 10,000 | |||||||||||||||||||||
| Bloomberg U.S. Aggregate Bond Index | |||||||||||||||||||||||||||||||||||||||||||
| Account Value [Line Items] | |||||||||||||||||||||||||||||||||||||||||||
| Account Value | 11,596 | 11,629 | 11,507 | 11,522 | 10,995 | 10,991 | 10,767 | 10,738 | 10,854 | 10,637 | 10,641 | 10,868 | 11,091 | 11,782 | 12,209 | 12,283 | 12,085 | 12,102 | 12,351 | 12,293 | 12,134 | 11,937 | 11,513 | 11,546 | 11,090 | 10,689 | 10,391 | 10,480 | 10,423 | 10,360 | 10,533 | 10,591 | 10,462 | 10,308 | 10,205 | 10,539 | 10,299 | 10,164 | 9,988 | 9,945 | 10,000 | ||
| Bloomberg U.S. Aggregate Bond Index | |||||||||||||||||||||||||||||||||||||||||||
| Account Value [Line Items] | |||||||||||||||||||||||||||||||||||||||||||
| Account Value | 578,967 | 580,641 | 574,546 | 575,290 | 548,998 | 548,768 | 537,586 | 536,167 | 541,923 | 531,097 | 531,318 | 542,642 | 553,790 | 588,290 | 609,586 | 613,265 | 603,401 | 604,268 | 616,699 | 613,783 | 605,854 | 596,021 | 574,830 | 576,466 | 553,719 | 533,674 | 518,841 | 523,239 | 520,411 | 517,277 | 525,899 | 528,788 | 522,367 | 514,678 | 509,522 | 526,197 | 514,249 | 507,495 | 498,692 | 500,000 | |||
| Bloomberg U.S. Aggregate Bond Index | |||||||||||||||||||||||||||||||||||||||||||
| Account Value [Line Items] | |||||||||||||||||||||||||||||||||||||||||||
| Account Value | 9,762 | 9,790 | 9,687 | 9,700 | 9,256 | 9,252 | 9,064 | 9,040 | 9,137 | 8,954 | 8,958 | 9,149 | 9,337 | 9,919 | 10,278 | 10,340 | 10,173 | 10,188 | 10,398 | 10,349 | 10,215 | 10,000 | |||||||||||||||||||||
| Bloomberg U.S. 1-5 Year Treasury TIPS Index | |||||||||||||||||||||||||||||||||||||||||||
| Account Value [Line Items] | |||||||||||||||||||||||||||||||||||||||||||
| Account Value | 13,136 | 12,940 | 12,679 | 12,569 | 12,280 | 12,112 | 11,958 | 11,813 | 11,786 | 11,611 | 11,636 | 11,867 | 12,032 | 12,117 | 12,029 | 11,947 | 11,779 | 11,522 | 11,324 | 11,301 | 10,973 | 10,947 | 10,743 | 10,738 | 10,597 | 10,397 | 10,281 | 10,356 | 10,306 | 10,214 | 10,242 | 10,264 | 10,252 | 10,244 | 10,148 | 10,134 | 10,068 | 9,968 | 9,899 | $ 9,931 | $ 10,000 | ||
| Bloomberg U.S. 1-5 Year Treasury TIPS Index | |||||||||||||||||||||||||||||||||||||||||||
| Account Value [Line Items] | |||||||||||||||||||||||||||||||||||||||||||
| Account Value | 662,718 | 652,854 | 639,675 | 634,125 | 619,531 | 611,082 | 603,290 | 595,981 | 594,610 | 585,787 | 587,040 | 598,723 | 607,030 | 611,344 | 606,900 | 602,738 | 594,261 | 581,310 | 571,332 | 570,149 | 553,588 | $ 552,305 | $ 542,017 | $ 541,759 | $ 534,639 | $ 524,564 | $ 518,712 | $ 522,505 | $ 519,957 | $ 515,333 | $ 516,723 | $ 517,856 | $ 517,259 | $ 516,820 | $ 511,988 | $ 511,268 | $ 507,945 | $ 502,888 | $ 499,443 | $ 500,000 | |||
| Bloomberg U.S. 1-5 Year Treasury TIPS Index | |||||||||||||||||||||||||||||||||||||||||||
| Account Value [Line Items] | |||||||||||||||||||||||||||||||||||||||||||
| Account Value | $ 12,325 | $ 12,142 | $ 11,897 | $ 11,793 | $ 11,522 | $ 11,365 | $ 11,220 | $ 11,084 | $ 11,058 | $ 10,894 | $ 10,918 | $ 11,135 | $ 11,289 | $ 11,370 | $ 11,287 | $ 11,210 | $ 11,052 | $ 10,811 | $ 10,626 | $ 10,604 | $ 10,296 | $ 10,000 |