Mortgages Payable and Debt Maturities - Summary of Debt Obligation and Interest Rate Derivatives (Detail) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Line of credit	$ 96,000	$ 49,000
Term notes	750,000	750,000
Mortgage note, total	2,061	2,127
Interest rate derivatives - liability	14,892	$ 13,341
Line of Credit - Variable Rate LIBOR + 1.30% (1.49% at June 30, 2015) [Member]
Debt Instrument [Line Items]
Payable due 2019	96,000
Line of credit	96,000
Debt instrument, fair value	96,000
Term Note - Fixed Rate 6.38% [Member]
Debt Instrument [Line Items]
Payables due 2016	150,000
Term notes	150,000
Term note, fair value	157,038
Term Note - Variable Rate LIBOR+1.40% (1.59% at June 30, 2015) [Member]
Debt Instrument [Line Items]
Payables due Thereafter	325,000
Term notes	325,000
Term note, fair value	325,000
Term Note - Fixed Rate 5.54% [Member]
Debt Instrument [Line Items]
Payables due Thereafter	100,000
Term notes	100,000
Term note, fair value	108,322
Term Note - Fixed Rate 4.533% [Member]
Debt Instrument [Line Items]
Payables due Thereafter	175,000
Term notes	175,000
Term note, fair value	174,782
Mortgage Note - Fixed Rate 5.99% [Member]
Debt Instrument [Line Items]
Payable due 2015	68
Payables due 2016	142
Payables due 2017	151
Payable due 2018	160
Payable due 2019	170
Payables due Thereafter	1,370
Mortgage note, total	2,061
Debt instrument, fair value	$ 2,181