|
Commitments and Contingencies - Additional Information (Detail) (USD $)
In Millions, unless otherwise specified |
9 Months Ended | |
|---|---|---|
|
Sep. 30, 2013
|
Dec. 31, 2012
|
|
| Commitments and Contingencies Disclosure [Abstract] | ||
| Total commitments | $ 54.5 | |
| Total commitments relating to future acquisitions | 48.7 | |
| Total commitments expected to be funded by December 31, 2013 | 50.6 | |
| Contingently liable amount of debt owed by tenant | 5.7 | |
| Estimated remediation liability | $ 0.1 | $ 0.1 |