Capital and Financing Transactions - Interest Rate Swap (Details) (USD $)	12 Months Ended					12 Months Ended						0 Months Ended									0 Months Ended	6 Months Ended
	Dec. 31, 2013 sqft	Sep. 28, 2012	May 31, 2012	Mar. 09, 2012 sqft	Feb. 10, 2012	Dec. 31, 2013 Designated as Hedging Instrument [Member] Cash Flow Hedging [Member]	Dec. 31, 2012 Designated as Hedging Instrument [Member] Cash Flow Hedging [Member]	Dec. 31, 2013 Hayden Ferry Lakeside II [Member] sqft	Jun. 28, 2013 Hayden Ferry Lakeside II [Member] sqft	Feb. 10, 2012 Hayden Ferry Lakeside II [Member]	Mar. 25, 2013 Fund II Assets [Member] Swap	Sep. 28, 2012 Term Loan Swap [Member]	Jun. 12, 2013 Term Loan Swap [Member]	Dec. 31, 2013 Accounts Payable and Other Liabilities [Member] Swap 2 [Member]	May 31, 2013 Accounts Payable and Other Liabilities [Member] Swap 13 [Member]	Dec. 31, 2013 Accounts Payable and Other Liabilities [Member] Swap 12 [Member]	Jun. 12, 2013 Accounts Payable and Other Liabilities [Member] Swap 12 [Member]	Mar. 25, 2013 Tampa Fund II Assets [Member]	Sep. 30, 2013 Wells Fargo Bank [Member] Unsecured Term Loan $120 million [Member]	Jun. 12, 2013 Wells Fargo Bank [Member] Unsecured Term Loan $120 million [Member]	Jun. 12, 2013 London Interbank Offered Rate (LIBOR) [Member] Working Capital Revolving Credit Facility [Member]	Jun. 27, 2013 Hayden Ferry II Original Mortgage [Member] Hayden Ferry Lakeside II [Member]	Jun. 28, 2013 Hayden Ferry II Original Mortgage [Member] Hayden Ferry Lakeside II [Member]	Aug. 01, 2013 Hayden Ferry II Modified Mortgage [Member] Hayden Ferry Lakeside II [Member]
Derivative [Line Items]
Mortgage notes payable										$ 50,000,000
Gain (loss) on interest rate cash flow hedge, ineffectiveness						127,000	0
Interest rate cash flow hedge gain (loss) to be reclassified near year						5,600,000
Accelerated gain (loss) reclassification from accumulated OCI into income						390,000
Rate at which reference rate is fixed	1.50%
Variable rate, minimum (in percent)					4.00%
Variable rate, maximum (in percent)					5.00%
Notional amount of swap assumed on sale			23,500,000
Derivative interest rate (in percent)		2.20%	5.80%											2.30%	3.30%	3.30%
Notional amount		125,000,000									34,600,000.0	125,000,000	120,000,000.0	30,000,000	13,500,000.0	120,000,000	120,000,000.0
Interest Rate	2.70%											0.70%								3.30%
Term loan facility swap terms (in years)												5 years 0 months 0 days									5 years
Ownership percentage of noncontrolling interest																		70.00%
Number of interest rate derivatives held											2
Outstanding balance	303,000,000																		120,000,000
LIBOR rate period fixed																					1.60%
Area of real estate property (in square feet)	17,600,000			337,000				300,000	299,000
Quarterly principal payment																						$ 625,000
Fixed base rate of variable interest rate																							1.50%	1.70%