Debt Financing (Details) € in Millions | 1 Months Ended | 2 Months Ended | 9 Months Ended | 12 Months Ended | | | |
Nov. 16, 2015USD ($)extension | Jul. 31, 2015extension | Jun. 30, 2015USD ($) | Nov. 16, 2015USD ($)extension | Sep. 30, 2015USD ($)extension | Dec. 31, 2014USD ($) | Nov. 13, 2015USD ($)extension | Mar. 31, 2015USD ($)instrument | Jan. 31, 2015EUR (€)€ / $ | Jan. 31, 2015USD ($)€ / $ |
Debt Instrument [Line Items] | | | | | | | | | | |
Debt, weighted average years to maturity | | | | | 3 years 29 days | 2 years 9 months | | | | |
Debt, weighted average interest rate (percent) | | | | | 2.40% | 2.90% | | | | |
Debt, Principal Outstanding | | | | | $ 2,504,711,000 | $ 2,112,642,000 | | | | |
Unamortized Premium/ (Discount) | | | | | 38,000 | (283,000) | | | | |
Notes Payable | | | | | 2,504,749,000 | 2,112,359,000 | | | | |
Notes payable to affiliates | | | | | 0 | 17,601,000 | | | | |
Debt outstanding | | | | | 2,504,749,000 | 2,129,960,000 | | | | |
Note payable, subject to interest rate swap | | | | | $ 95,000,000 | 236,000,000 | | | | |
Debt instrument, description of variable rate basis | | | | | LIBOR, EURIBOR or the BBSY screen rate | | | | | |
Minimum [Member] | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | |
Cap interest rate (percent) | | | | | 0.80% | | | | | |
Debt instrument, basis spread on variable rate | | | | | 0.70% | | | | | |
Maximum [Member] | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | |
Cap interest rate (percent) | | | | | 4.50% | | | | | |
Debt instrument, basis spread on variable rate | | | | | 2.50% | | | | | |
Interest Rate Caps [Member] | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | |
Derivative, notional amount | | | | | $ 1,000,000,000 | | | | | |
Secured Debt [Member] | Fifty South Sixth [Member] | Subsequent Event [Member] | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | |
Number of extension options, debt | extension | | | | | | | 2 | | | |
Period of extension options, debt | 12 months | | | | | | | | | |
Amended debt instrument, face amount | | | | | | | $ 125,000,000 | | | |
Secured Debt [Member] | The Campus at Playa Vista [Member] | Subsequent Event [Member] | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | |
Number of extension options, debt | extension | 2 | | | 2 | | | | | | |
Period of extension options, debt | 12 months | | | | | | | | | |
Amended debt instrument, face amount | $ 150,000,000 | | | $ 150,000,000 | | | | | | |
Secured Debt [Member] | Flagship Capital Joint Venture [Member] | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | |
Variable interest rate, floor | | | | | 4.25% | | | | | |
Credit facility, Interest Rate (percent) | | | | | 4.25% | | | | | |
Credit facility, principal outstanding | | | | | $ 14,207,000 | 25,162,000 | | | | |
Secured Debt [Member] | Brindleyplace JV [Member] | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | |
Interest Rate at period end (percent) | | | | | 2.02% | | | | | |
Debt, Principal Outstanding | | | | | $ 183,579,000 | 188,034,000 | | | | |
Secured Debt [Member] | Brindleyplace JV [Member] | Secured mortgage debt, three-month extension [Member] | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | |
Number of extension options, debt | extension | | 2 | | | | | | | | |
Period of extension options, debt | | 3 months | | | | | | | | |
Secured Debt [Member] | Brindleyplace JV [Member] | Secured mortgage debt, six-month extension [Member] | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | |
Number of extension options, debt | extension | | 1 | | | | | | | | |
Period of extension options, debt | | 6 months | | | | | | | | |
Secured Debt [Member] | Hock Plaza [Member] | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | |
Interest Rate at period end (percent) | | | | | 5.58% | | | | | |
Debt, Principal Outstanding | | | | | $ 74,728,000 | 75,657,000 | | | | |
Secured Debt [Member] | Southpark [Member] | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | |
Interest Rate at period end (percent) | | | | | 5.67% | | | | | |
Debt, Principal Outstanding | | | | | $ 18,000,000 | 18,000,000 | | | | |
Secured Debt [Member] | Fifty South Sixth [Member] | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | |
Interest Rate at period end (percent) | | | | | 3.62% | | | | | |
Debt, Principal Outstanding | | | | | $ 95,000,000 | 95,000,000 | | | | |
Secured Debt [Member] | Gogolevsky 11 [Member] | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | |
Debt, Principal Outstanding | | | | | $ 0 | 35,100,000 | | | | |
Secured Debt [Member] | 100 Brookes Street [Member] | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | |
Reduction in margin on variable rate debt | | | | | 0.35% | | | | | |
Interest Rate at period end (percent) | | | | | 4.48% | | | | | |
Debt, Principal Outstanding | | | | | $ 30,154,000 | 35,254,000 | | | | |
Secured Debt [Member] | Poland Logistics Portfolio [Member] | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | |
Interest Rate at period end (percent) | | | | | 2.00% | | | | | |
Debt, Principal Outstanding | | | | | $ 69,844,000 | 76,797,000 | | | | |
Secured Debt [Member] | Minneapolis Retail Center [Member] | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | |
Interest Rate at period end (percent) | | | | | 3.50% | | | | | |
Debt, Principal Outstanding | | | | | $ 65,500,000 | 65,500,000 | | | | |
Secured Debt [Member] | 825 Ann [Member] | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | |
Interest Rate at period end (percent) | | | | | 3.19% | | | | | |
Debt, Principal Outstanding | | | | | $ 56,529,000 | 66,091,000 | | | | |
Secured Debt [Member] | Mercedes Benz Bank [Member] | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | |
Interest Rate at period end (percent) | | | | | 1.55% | | | | | |
Debt, Principal Outstanding | | | | | $ 37,951,000 | 41,346,000 | | | | |
Secured Debt [Member] | 465 Victoria [Member] | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | |
Interest Rate at period end (percent) | | | | | 4.23% | | | | | |
Debt, Principal Outstanding | | | | | $ 37,118,000 | 43,396,000 | | | | |
Secured Debt [Member] | New City [Member] | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | |
Interest Rate at period end (percent) | | | | | 2.30% | | | | | |
Debt, Principal Outstanding | | | | | $ 86,886,000 | 95,934,000 | | | | |
Secured Debt [Member] | One Westferry Circus [Member] | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | |
Interest Rate at period end (percent) | | | | | 3.30% | | | | | |
Debt, Principal Outstanding | | | | | $ 72,787,000 | 74,554,000 | | | | |
Secured Debt [Member] | The Campus at Playa Vista [Member] | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | |
Interest Rate at period end (percent) | | | | | 1.70% | | | | | |
Debt, Principal Outstanding | | | | | $ 115,000,000 | 115,000,000 | | | | |
Secured Debt [Member] | Perspective Defense [Member] | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | |
Interest Rate at period end (percent) | | | | | 2.48% | | | | | |
Debt, Principal Outstanding | | | | | $ 78,701,000 | 85,085,000 | | | | |
Secured Debt [Member] | Fiege Mega Centre [Member] | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | |
Interest Rate at period end (percent) | | | | | 1.69% | | | | | |
Debt, Principal Outstanding | | | | | $ 25,995,000 | 28,373,000 | | | | |
Secured Debt [Member] | 55 M Street [Member] | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | |
Interest Rate at period end (percent) | | | | | 1.64% | | | | | |
Debt, Principal Outstanding | | | | | $ 72,000,000 | 72,000,000 | | | | |
Secured Debt [Member] | 25 Cabot Square [Member] | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | |
Interest Rate at period end (percent) | | | | | 3.50% | | | | | |
Debt, Principal Outstanding | | | | | $ 187,655,000 | 192,209,000 | | | | |
Secured Debt [Member] | Simon Hegele Logistics [Member] | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | |
Interest Rate at period end (percent) | | | | | 1.90% | | | | | |
Debt, Principal Outstanding | | | | | $ 40,245,000 | 26,106,000 | | | | |
Secured Debt [Member] | 818 Bourke [Member] | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | |
Interest Rate at period end (percent) | | | | | 2.89% | | | | | |
Debt, Principal Outstanding | | | | | $ 62,958,000 | 74,627,000 | | | | |
Secured Debt [Member] | The Summit [Member] | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | |
Interest Rate at period end (percent) | | | | | 1.75% | | | | | |
Debt, Principal Outstanding | | | | | $ 170,000,000 | 0 | | | | |
Secured Debt [Member] | Harder Logistics Portfolio [Member] | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | |
Interest Rate at period end (percent) | | | | | 0.95% | | | | | |
Debt, Principal Outstanding | | | | | $ 35,284,000 | 0 | | | | |
Secured Debt [Member] | Simon Hegele Logistics Phase II [Member] | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | |
Debt, Principal Outstanding | | | | | | | | | € 14.6 | $ 17,800,000 |
Foreign currency exchange rate (usd per eur) (aud per usd) | € / $ | | | | | | | | | 1.22 | 1.22 |
Revolving Credit Facility- Revolving Loan [Member] | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | |
Credit facility, Interest Rate (percent) | | | | | 1.80% | | | | | |
Credit facility, principal outstanding | | | | | $ 292,000,000 | 122,894,000 | | | | |
Loan commitments, borrowing capacity | | | $ 425,000,000 | | | | | | | |
Credit agreement, extension option, term | | | 1 year | | | | | | | |
Revolving Credit Facility- Term Loan [Member] | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | |
Credit facility, Interest Rate (percent) | | | | | 1.75% | | | | | |
Credit facility, principal outstanding | | | | | $ 495,000,000 | 378,000,000 | | | | |
Loan commitments, borrowing capacity | | | $ 495,000,000 | | | | | | | |
Construction Loan Payable [Member] | Water Wall Place [Member] | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | |
Interest Rate at period end (percent) | | | | | 1.79% | | | | | |
Debt, Principal Outstanding | | | | | $ 44,897,000 | 44,092,000 | | | | |
Number of extension options, debt | extension | | | | | 2 | | | | | |
Period of extension options, debt | | | | | 1 year | | | | | |
Construction Loan Payable [Member] | Aviva Coral Gables JV [Member] | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | |
Interest Rate at period end (percent) | | | | | 2.46% | | | | | |
Debt, Principal Outstanding | | | | | $ 42,693,000 | 38,431,000 | | | | |
Construction Loan Payable [Member] | Aviva Coral Gables JV [Member] | Affiliated Entity [Member] | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | |
Notes payable to affiliates | | | | | 0 | $ 17,601,000 | | | | |
Revolving Credit Facility (Including Revolving and Term Loans) [Member] | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | |
Loan commitments, borrowing capacity | | | 920,000,000 | | | | | | | |
Credit agreement, maximum borrowing capacity | | | $ 1,250,000,000 | | | | | | | |
Credit facility, additional borrowings | | | | | 1,100,000,000 | | | | | |
Repayments of revolving credit facility | | | | | 824,700,000 | | | | | |
Gain on foreign currency borrowings | | | | | $ 200,000 | | | | | |
Revolving Credit Facility (Including Revolving and Term Loans) [Member] | Subsequent Event [Member] | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | |
Credit facility, principal outstanding | $ 877,000,000 | | | 877,000,000 | | | | | | |
Credit facility, additional borrowings | | | | $ 90,000,000 | | | | | | |
Revolving Credit Facility (Including Revolving and Term Loans) [Member] | Minimum [Member] | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | |
Cap interest rate (percent) | | | | | | | | 0.75% | | |
Revolving Credit Facility (Including Revolving and Term Loans) [Member] | Maximum [Member] | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | |
Cap interest rate (percent) | | | | | | | | 2.25% | | |
Revolving Credit Facility (Including Revolving and Term Loans) [Member] | Interest Rate Caps [Member] | | | | | | | | | | |
Debt Instrument [Line Items] | | | | | | | | | | |
Number of derivative instruments | instrument | | | | | | | | 2 | | |
Derivative, notional amount | | | | | | | | $ 250,000,000 | | |