Schedule III - Real Estate and Accumulated Depreciation (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Mortgage Encumbrances	$ 444,933
Initial Cost to Registrant, Land	76,860
Initial Cost to Registrant, Building and Improvements	573,535
Cost capitalized/(impaired) subsequent to acquisition Land/Building and Improvements	21,401
Land	82,215
Building and Improvements	588,653
Total	670,868		421,989	363,832	308,499
Accumulated Depreciation	56,448		51,553	44,556	36,232
Office [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Mortgage Encumbrances	252,057
Initial Cost to Registrant, Land	41,519
Initial Cost to Registrant, Building and Improvements	265,878
Cost capitalized/(impaired) subsequent to acquisition Land/Building and Improvements	34,568
Land	46,501
Building and Improvements	294,536
Total	341,037
Accumulated Depreciation	45,103
Office [Member] | Orlando [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Mortgage Encumbrances	36,983
Initial Cost to Registrant, Land
Initial Cost to Registrant, Building and Improvements	17,248
Cost capitalized/(impaired) subsequent to acquisition Land/Building and Improvements	42
Land
Building and Improvements	17,290
Total	17,290
Accumulated Depreciation	3,944
Date Acquired	2004-11
Life [1]		[1]
Office [Member] | Plantation [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Mortgage Encumbrances	10,684
Initial Cost to Registrant, Land
Initial Cost to Registrant, Building and Improvements	8,915
Cost capitalized/(impaired) subsequent to acquisition Land/Building and Improvements	4,020
Land	4,000
Building and Improvements	8,935
Total	12,935
Accumulated Depreciation	2,038
Date Acquired	2004-11
Life [1]		[1]
Office [Member] | Chicago 1 [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Mortgage Encumbrances	19,856
Initial Cost to Registrant, Land
Initial Cost to Registrant, Building and Improvements	23,635
Cost capitalized/(impaired) subsequent to acquisition Land/Building and Improvements	2,875
Land
Building and Improvements	26,510
Total	26,510
Accumulated Depreciation	5,792
Date Acquired	2005-10
Life [1]		[1]
Office [Member] | Amherst [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Mortgage Encumbrances
Initial Cost to Registrant, Land	1,591
Initial Cost to Registrant, Building and Improvements	18,027
Cost capitalized/(impaired) subsequent to acquisition Land/Building and Improvements	1,377
Land	2,573
Building and Improvements	18,422
Total	20,995
Accumulated Depreciation	3,887
Date Acquired	2005-05
Life [1]		[1]
Office [Member] | South Burlington [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Mortgage Encumbrances
Initial Cost to Registrant, Land
Initial Cost to Registrant, Building and Improvements	3,099
Cost capitalized/(impaired) subsequent to acquisition Land/Building and Improvements	309
Land
Building and Improvements	3,408
Total	3,408
Accumulated Depreciation	671
Date Acquired	2005-12
Life [1]		[1]
Office [Member] | Chicago 2 [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Mortgage Encumbrances	8,579
Initial Cost to Registrant, Land	1,149
Initial Cost to Registrant, Building and Improvements	9,989
Cost capitalized/(impaired) subsequent to acquisition Land/Building and Improvements	5,631
Land	1,149
Building and Improvements	15,620
Total	16,769
Accumulated Depreciation	2,517
Date Acquired	2007-10
Life [1]		[1]
Office [Member] | Houston [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Mortgage Encumbrances	47,201
Initial Cost to Registrant, Land	7,075
Initial Cost to Registrant, Building and Improvements	62,468
Land	7,075
Building and Improvements	62,468
Total	69,543
Accumulated Depreciation	14,185
Date Acquired	2005-01
Life [1]		[1]
Office [Member] | Lisle 1 [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Mortgage Encumbrances	5,752
Initial Cost to Registrant, Land	3,774
Initial Cost to Registrant, Building and Improvements	16,371
Cost capitalized/(impaired) subsequent to acquisition Land/Building and Improvements	2,461
Land	3,774
Building and Improvements	18,832
Total	22,606
Accumulated Depreciation	3,779
Date Acquired	2006-02
Life [1]		[1]
Office [Member] | Lisle 2 [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Mortgage Encumbrances	5,470
Initial Cost to Registrant, Land	780
Initial Cost to Registrant, Building and Improvements	2,803
Cost capitalized/(impaired) subsequent to acquisition Land/Building and Improvements	689
Land	780
Building and Improvements	3,492
Total	4,272
Accumulated Depreciation	635
Date Acquired	2006-02
Life [1]		[1]
Office [Member] | Englewood 1 [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Mortgage Encumbrances
Initial Cost to Registrant, Land	2,580
Initial Cost to Registrant, Building and Improvements	5,403
Cost capitalized/(impaired) subsequent to acquisition Land/Building and Improvements	3,347
Land	2,580
Building and Improvements	8,750
Total	11,330
Accumulated Depreciation	1,341
Date Acquired	2010-11
Life [1]		[1]
Office [Member] | Englewood 2 [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Mortgage Encumbrances
Initial Cost to Registrant, Land	1,829
Initial Cost to Registrant, Building and Improvements	5,612
Cost capitalized/(impaired) subsequent to acquisition Land/Building and Improvements	717
Land	1,829
Building and Improvements	6,329
Total	8,158
Accumulated Depreciation	875
Date Acquired	2010-12
Life [1]		[1]
Office [Member] | New York, NY [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Mortgage Encumbrances	51,950
Initial Cost to Registrant, Land
Initial Cost to Registrant, Building and Improvements	52,778
Cost capitalized/(impaired) subsequent to acquisition Land/Building and Improvements	7,469
Land
Building and Improvements	60,247
Total	60,247
Accumulated Depreciation	3,740
Date Acquired	2011-11
Life [1]		[1]
Office [Member] | Cerritos [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Mortgage Encumbrances	23,142
Initial Cost to Registrant, Land	4,114
Initial Cost to Registrant, Building and Improvements	16,190
Cost capitalized/(impaired) subsequent to acquisition Land/Building and Improvements	3,419
Land	4,114
Building and Improvements	18,681
Total	22,795
Accumulated Depreciation	911
Date Acquired	2012-10
Life [1]		[1]
Office [Member] | Philadelphia [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Mortgage Encumbrances	42,440
Initial Cost to Registrant, Land	18,627
Initial Cost to Registrant, Building and Improvements	23,340
Cost capitalized/(impaired) subsequent to acquisition Land/Building and Improvements	2,212
Land	18,627
Building and Improvements	25,552
Total	44,179
Accumulated Depreciation	788
Date Acquired	2013-02
Life [1]		[1]
Retail [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Mortgage Encumbrances
Initial Cost to Registrant, Land
Initial Cost to Registrant, Building and Improvements	11,152
Cost capitalized/(impaired) subsequent to acquisition Land/Building and Improvements	(2,294)
Land	373
Building and Improvements	8,485
Total	8,858
Accumulated Depreciation	1,631
Retail [Member] | Atlanta [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Mortgage Encumbrances
Initial Cost to Registrant, Land
Initial Cost to Registrant, Building and Improvements	4,633
Cost capitalized/(impaired) subsequent to acquisition Land/Building and Improvements	(2,675)
Land
Building and Improvements	1,958
Total	1,958
Accumulated Depreciation	142
Date Acquired	2004-11
Life [1]		[1]
Retail [Member] | Louisville [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Mortgage Encumbrances
Initial Cost to Registrant, Land
Initial Cost to Registrant, Building and Improvements	2,722
Cost capitalized/(impaired) subsequent to acquisition Land/Building and Improvements	377
Land	373
Building and Improvements	2,726
Total	3,099
Accumulated Depreciation	622
Date Acquired	2004-11
Life [1]		[1]
Retail [Member] | Greensboro [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Mortgage Encumbrances
Initial Cost to Registrant, Land
Initial Cost to Registrant, Building and Improvements	3,797
Cost capitalized/(impaired) subsequent to acquisition Land/Building and Improvements	4
Land
Building and Improvements	3,801
Total	3,801
Accumulated Depreciation	867
Date Acquired	2004-11
Life [1]		[1]
Other [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Mortgage Encumbrances	192,876
Initial Cost to Registrant, Land	35,341
Initial Cost to Registrant, Building and Improvements	296,505
Cost capitalized/(impaired) subsequent to acquisition Land/Building and Improvements	(10,873)
Land	35,341
Building and Improvements	285,632
Total	320,973
Accumulated Depreciation	9,714
Other [Member] | Houston [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Mortgage Encumbrances	64,635
Initial Cost to Registrant, Land	16,167
Initial Cost to Registrant, Building and Improvements	88,769
Cost capitalized/(impaired) subsequent to acquisition Land/Building and Improvements
Land	16,167
Building and Improvements	88,769
Total	104,936
Accumulated Depreciation	417
Date Acquired	2013-10
Life [1]		[1]
Other [Member] | Greensboro [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Mortgage Encumbrances	14,735
Initial Cost to Registrant, Land	1,961
Initial Cost to Registrant, Building and Improvements	16,482
Cost capitalized/(impaired) subsequent to acquisition Land/Building and Improvements	132
Land	1,961
Building and Improvements	16,614
Total	18,575
Accumulated Depreciation	766
Date Acquired	2012-11
Life [1]		[1]
Other [Member] | Jacksonville [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Mortgage Encumbrances
Initial Cost to Registrant, Land	2,166
Initial Cost to Registrant, Building and Improvements	8,684
Cost capitalized/(impaired) subsequent to acquisition Land/Building and Improvements	2,241
Land	2,166
Building and Improvements	10,925
Total	13,091
Accumulated Depreciation	2,541
Date Acquired	2004-11
Life [1]		[1]
Other [Member] | Churchill [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Mortgage Encumbrances	5,049
Initial Cost to Registrant, Land
Initial Cost to Registrant, Building and Improvements	23,834
Cost capitalized/(impaired) subsequent to acquisition Land/Building and Improvements	(14,129)
Land
Building and Improvements	9,705
Total	9,705
Accumulated Depreciation	4,176
Date Acquired	2004-11
Life [1]		[1]
Other [Member] | Memphis [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Mortgage Encumbrances	13,125
Initial Cost to Registrant, Land	3,080
Initial Cost to Registrant, Building and Improvements	17,485
Cost capitalized/(impaired) subsequent to acquisition Land/Building and Improvements	883
Land	3,080
Building and Improvements	18,368
Total	21,448
Accumulated Depreciation	1,150
Date Acquired	2012-04
Life [1]		[1]
Other [Member] | Oklahoma City [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Mortgage Encumbrances	9,967
Initial Cost to Registrant, Land	1,328
Initial Cost to Registrant, Building and Improvements	13,351
Cost capitalized/(impaired) subsequent to acquisition Land/Building and Improvements
Land	1,328
Building and Improvements	13,351
Total	14,679
Accumulated Depreciation	70
Date Acquired	2013-10
Life [1]		[1]
Other [Member] | Phoenix [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Mortgage Encumbrances	24,390
Initial Cost to Registrant, Land	1,053
Initial Cost to Registrant, Building and Improvements	38,488
Cost capitalized/(impaired) subsequent to acquisition Land/Building and Improvements
Land	1,053
Building and Improvements	38,488
Total	39,541
Accumulated Depreciation	181
Date Acquired	2013-10
Life [1]		[1]
Other [Member] | San Pedro [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Mortgage Encumbrances	12,195
Initial Cost to Registrant, Land	3,879
Initial Cost to Registrant, Building and Improvements	15,952
Cost capitalized/(impaired) subsequent to acquisition Land/Building and Improvements
Land	3,879
Building and Improvements	15,952
Total	19,831
Accumulated Depreciation	98
Date Acquired	2013-10
Life [1]		[1]
Other [Member] | Stamford [Member]
SEC Schedule III, Real Estate and Accumulated Depreciation [Line Items]
Mortgage Encumbrances	48,780
Initial Cost to Registrant, Land	5,707
Initial Cost to Registrant, Building and Improvements	73,460
Cost capitalized/(impaired) subsequent to acquisition Land/Building and Improvements
Land	5,707
Building and Improvements	73,460
Total	79,167
Accumulated Depreciation	$ 315
Date Acquired	2013-10
Life [1]		[1]

[1] Buildings are depreciated over 30-40 years. Building improvements are depreciated over 5-20 years. Tenant improvements are depreciated over the shorter of the useful life on the term of the [ILLEGIBLE]