| Document and Entity Information Document | Sep. 18, 2019 |
| Cover page. | |
| Document Type | 8-K |
| Document Period End Date | Sep. 18, 2019 |
| Entity Registrant Name | HCP, INC. |
| Entity Central Index Key | 0000765880 |
| Amendment Flag | false |
| Entity Incorporation, State or Country Code | MD |
| Entity File Number | 001-08895 |
| Entity Tax Identification Number | 33-0091377 |
| Entity Address, Address Line One | 1920 Main Street |
| Entity Address, Address Line Two | Suite 1200 |
| Entity Address, City or Town | Irvine |
| Entity Address, State or Province | CA |
| Entity Address, Postal Zip Code | 92614 |
| City Area Code | 949 |
| Local Phone Number | 407-0700 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock |
| Trading Symbol | HCP |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
