Parent Directory| Name | Size | Last Modified |
|---|---|---|
 0000919574-14-002516-index-headers.html | 2014-04-04 16:12:28 | |
| 0000919574-14-002516-index.html | 2014-04-04 16:12:28 | |
| 0000919574-14-002516.txt | 2014-04-04 16:12:28 | |
 0000919574-14-002516-xbrl.zip | 187492 | 2014-04-04 16:12:28 |
| d1458032_20-f.htm | 2338603 | 2014-04-04 16:12:28 |
| d1467062_ex8-1.htm | 6065 | 2014-04-04 16:12:28 |
| d1467093_ex12-1.htm | 8700 | 2014-04-04 16:12:28 |
| d1467093_ex12-2.htm | 8661 | 2014-04-04 16:12:28 |
| d1467093_ex13-1.htm | 5172 | 2014-04-04 16:12:28 |
| d1467093_ex13-2.htm | 5007 | 2014-04-04 16:12:28 |
| d1467095_ex15-1.htm | 4167 | 2014-04-04 16:12:28 |
| FilingSummary.xml | 29375 | 2014-04-04 16:12:28 |
| Financial_Report.xls | 868033 | 2014-04-04 16:12:28 |
| Financial_Report.xlsx | 151454 | 2014-04-04 16:12:28 |
| nat-20131231.xml | 977563 | 2014-04-04 16:12:28 |
| nat-20131231.xsd | 72541 | 2014-04-04 16:12:28 |
| nat-20131231_cal.xml | 73147 | 2014-04-04 16:12:28 |
| nat-20131231_def.xml | 254756 | 2014-04-04 16:12:28 |
| nat-20131231_lab.xml | 808908 | 2014-04-04 16:12:28 |
| nat-20131231_pre.xml | 452775 | 2014-04-04 16:12:28 |
| R1.htm | 36401 | 2014-04-04 16:12:28 |
| R10.htm | 39103 | 2014-04-04 16:12:28 |
| R11.htm | 17201 | 2014-04-04 16:12:28 |
| R12.htm | 19453 | 2014-04-04 16:12:28 |
| R13.htm | 31866 | 2014-04-04 16:12:28 |
| R14.htm | 10220 | 2014-04-04 16:12:28 |
| R15.htm | 20325 | 2014-04-04 16:12:28 |
| R16.htm | 8183 | 2014-04-04 16:12:28 |
| R17.htm | 16519 | 2014-04-04 16:12:28 |
| R18.htm | 35401 | 2014-04-04 16:12:28 |
| R19.htm | 48709 | 2014-04-04 16:12:28 |
| R2.htm | 70328 | 2014-04-04 16:12:28 |
| R20.htm | 9544 | 2014-04-04 16:12:28 |
| R21.htm | 6620 | 2014-04-04 16:12:28 |
| R22.htm | 12630 | 2014-04-04 16:12:28 |
| R23.htm | 25439 | 2014-04-04 16:12:28 |
| R24.htm | 45861 | 2014-04-04 16:12:28 |
| R25.htm | 9494 | 2014-04-04 16:12:28 |
| R26.htm | 35509 | 2014-04-04 16:12:28 |
| R27.htm | 8167 | 2014-04-04 16:12:28 |
| R28.htm | 123136 | 2014-04-04 16:12:28 |
| R29.htm | 25466 | 2014-04-04 16:12:28 |
| R3.htm | 28546 | 2014-04-04 16:12:28 |
| R30.htm | 15746 | 2014-04-04 16:12:28 |
| R31.htm | 29937 | 2014-04-04 16:12:28 |
| R32.htm | 18755 | 2014-04-04 16:12:28 |
| R33.htm | 15464 | 2014-04-04 16:12:28 |
| R34.htm | 25675 | 2014-04-04 16:12:28 |
| R35.htm | 40330 | 2014-04-04 16:12:28 |
| R36.htm | 10888 | 2014-04-04 16:12:28 |
| R37.htm | 23847 | 2014-04-04 16:12:28 |
| R38.htm | 33376 | 2014-04-04 16:12:28 |
| R39.htm | 26360 | 2014-04-04 16:12:28 |
| R4.htm | 122447 | 2014-04-04 16:12:28 |
| R40.htm | 28477 | 2014-04-04 16:12:28 |
| R41.htm | 78404 | 2014-04-04 16:12:28 |
| R42.htm | 89571 | 2014-04-04 16:12:28 |
| R43.htm | 45432 | 2014-04-04 16:12:28 |
| R44.htm | 39840 | 2014-04-04 16:12:28 |
| R45.htm | 19287 | 2014-04-04 16:12:28 |
| R46.htm | 26516 | 2014-04-04 16:12:28 |
| R47.htm | 34257 | 2014-04-04 16:12:28 |
| R48.htm | 26300 | 2014-04-04 16:12:28 |
| R49.htm | 127657 | 2014-04-04 16:12:28 |
| R5.htm | 15886 | 2014-04-04 16:12:28 |
| R50.htm | 118578 | 2014-04-04 16:12:28 |
| R51.htm | 26346 | 2014-04-04 16:12:28 |
| R52.htm | 12558 | 2014-04-04 16:12:28 |
| R53.htm | 16322 | 2014-04-04 16:12:28 |
| R54.htm | 32861 | 2014-04-04 16:12:28 |
| R55.htm | 92859 | 2014-04-04 16:12:28 |
| R56.htm | 12359 | 2014-04-04 16:12:28 |
| R57.htm | 30001 | 2014-04-04 16:12:28 |
| R58.htm | 24183 | 2014-04-04 16:12:28 |
| R6.htm | 83396 | 2014-04-04 16:12:28 |
| R7.htm | 5700 | 2014-04-04 16:12:28 |
| R8.htm | 140551 | 2014-04-04 16:12:28 |
| R9.htm | 31598 | 2014-04-04 16:12:28 |
| report.css | 2740 | 2014-04-04 16:12:28 |
| Show.js | 1410 | 2014-04-04 16:12:28 |