Real Estate Allocation of Purchase Price (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012
Business Acquisition [Line Items]
Land	$ 48,706
Building	213,596
Land improvements	888
Tenant improvements	6,884
Total real estate	270,074
Lease intangibles	17,028
Prepaid expenses and other assets	3,011
Total assets	290,113
Accounts payable and accrued expenses	550
Security deposits payable	815
Lease intangibles	11,239
Other liabilities and deferred credits	519
Total liabilities	13,123
One Beach Street
Business Acquisition [Line Items]
Land	15,332
Building	16,764
Land improvements	30
Tenant improvements	1,223
Total real estate	33,349
Lease intangibles	4,141
Prepaid expenses and other assets	1
Total assets	37,491
Accounts payable and accrued expenses	94
Security deposits payable	75
Lease intangibles	1,382
Other liabilities and deferred credits	22
Total liabilities	1,573
City Center Bellevue
Business Acquisition [Line Items]
Land	25,135
Building	185,653
Land improvements	154
Tenant improvements	5,191
Total real estate	216,133
Lease intangibles	11,870
Prepaid expenses and other assets	2,596
Total assets	230,599
Accounts payable and accrued expenses	456
Security deposits payable	740
Lease intangibles	8,733
Other liabilities and deferred credits	497
Total liabilities	10,426
Geary Marketplace
Business Acquisition [Line Items]
Land	8,239
Building	11,179
Land improvements	704
Tenant improvements	470
Total real estate	20,592
Lease intangibles	1,017
Prepaid expenses and other assets	414
Total assets	22,023
Accounts payable and accrued expenses	0
Security deposits payable	0
Lease intangibles	1,124
Other liabilities and deferred credits	0
Total liabilities	$ 1,124