Quarterly report pursuant to Section 13 or 15(d)

Commitments and Contingencies - Future Minimum Rental Payments Due under Terms of Leases (Detail)

v2.4.0.8
Commitments and Contingencies - Future Minimum Rental Payments Due under Terms of Leases (Detail) (USD $)
In Thousands, unless otherwise specified
6 Months Ended
Jun. 30, 2013
Operating Leased Assets [Line Items]  
2013 $ 27,152
2014 54,022
2015 52,560
2016 49,330
2017 47,279
2018 45,230
Thereafter 255,699
Ground Leases [Member]
 
Operating Leased Assets [Line Items]  
2013 206
2014 413
2015 413
2016 413
2017 416
2018 417
Thereafter 4,916
Ground Leases [Member] | Tulsa, OK [Member]
 
Operating Leased Assets [Line Items]  
Lease End Date 2021-04
2013 76
2014 153
2015 153
2016 153
2017 153
2018 153
Thereafter 381
Ground Leases [Member] | Dartmouth, MA [Member]
 
Operating Leased Assets [Line Items]  
Lease End Date 2036-05
2013 87
2014 174
2015 174
2016 174
2017 174
2018 174
Thereafter 3,472
Ground Leases [Member] | Springfield, MA [Member]
 
Operating Leased Assets [Line Items]  
Lease End Date 2030-02
2013 43
2014 86
2015 86
2016 86
2017 89
2018 90
Thereafter $ 1,063