XML 41 R19.htm IDEA: XBRL DOCUMENT
v3.21.2

Stockholders' Equity Stockholders' Equity (Tables) | 9 Months Ended
--- | ---
Sep. 30, 2021
Stockholders' Equity Attributable to Parent [Abstract] |
Quarterly dividends declared [Table Text Block] | The Board declared quarterly dividends as follows:
(amounts per share) | 2021 |  | 2020
First quarter | $ | 0.40 |  |  | $ | 0.40 |
Second quarter | 0.45 |  |  | 0.40 |
Third quarter | 0.45 |  |  | 0.40 |

X
- Definition Quarterly dividends declared [Table Text Block] - tabular disclosure of all or some of the information related to dividends declared and paid as of the financial reporting date. + References No definition available. + Details
Name: | nsp_QuarterlydividendsdeclaredTableTextBlock
Namespace Prefix: | nsp_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_StockholdersEquityAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration