| Document and Entity Information | Apr. 02, 2021 |
| Cover [Abstract] | |
| Amendment Flag | false |
| Entity Central Index Key | 0001590955 |
| Document Type | 8-K |
| Document Period End Date | Apr. 2, 2021 |
| Entity Registrant Name | Paycom Software, Inc. |
| Entity Incorporation State Country Code | DE |
| Entity File Number | 001-36393 |
| Entity Tax Identification Number | 80-0957485 |
| Entity Address, Address Line One | 7501 W. Memorial Road |
| Entity Address, City or Town | Oklahoma City |
| Entity Address, State or Province | OK |
| Entity Address, Postal Zip Code | 73142 |
| City Area Code | (405) |
| Local Phone Number | 722-6900 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Security 12b Title | Common Stock, $0.01 par value |
| Trading Symbol | PAYC |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
