SCHEDULE III - REAL ESTATE AND ACCUMULATED DEPRECIATION (Details) (USD $)	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012	Dec. 31, 2011
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	$ 1,081,597,000	[1]
Initial Cost to the Company [Abstract]
Land	278,781,000
Building and Improvements	1,974,581,000
Subsequent Capitalized Costs	294,674,000
Total Real Estate	2,548,036,000	[2]	1,762,566,000	1,084,060,000
Gross Amounts at Which Carried at Close of Period [Abstract]
Land	278,781,000
Building and Improvements	2,269,255,000
Total Real Estate	2,548,036,000	[2]	1,762,566,000	1,084,060,000
Accumulated Depreciation	231,241,000		199,849,000	162,123,000
Net investment in office and parking properties	2,316,795,000		1,562,717,000
Estimated useful life of depreciable assets	40 years
Aggregate cost for federal income tax	2,700,000,000
Real Estate [Roll Forward]
Balance at beginning of year	1,762,566,000		1,084,060,000	1,755,919,000
Additions [Abstract]
Acquisitions and improvements	911,641,000		710,642,000	535,249,000
Impairment on land held for development	(24,258,000)		0	(609,000)
Real estate sold, disposed, impaired or held for sale	(101,913,000)		(32,136,000)	(1,206,499,000)
Balance at close of year	2,548,036,000	[2]	1,762,566,000	1,084,060,000
Accumulated Depreciation [Roll Forward]
Balance at beginning of year	199,849,000		162,123,000	366,152,000
Depreciation expense	69,027,000		50,421,000	32,971,000
Depreciation expense - discontinued operations	(23,579,000)		316,000	43,578,000
Real estate sold, disposed, impaired or held for sale	(14,056,000)		(13,011,000)	(280,578,000)
Balance at close of year	231,241,000		199,849,000	162,123,000
ARIZONA | Hayden Ferry Lakeside I [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	22,000,000	[1]
Initial Cost to the Company [Abstract]
Land	2,871,000
Building and Improvements	30,430,000
Subsequent Capitalized Costs	5,830,000
Total Real Estate	39,131,000	[2]
Gross Amounts at Which Carried at Close of Period [Abstract]
Land	2,871,000
Building and Improvements	36,260,000
Total Real Estate	39,131,000	[2]
Accumulated Depreciation	3,930,000
Net investment in office and parking properties	35,201,000
Year Acquired	2011
Year constructed	2002
Additions [Abstract]
Balance at close of year	39,131,000	[2]
Accumulated Depreciation [Roll Forward]
Balance at close of year	3,930,000
ARIZONA | Hayden Ferry Lakeside II [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	46,875,000	[1]
Initial Cost to the Company [Abstract]
Land	3,612,000
Building and Improvements	69,248,000
Subsequent Capitalized Costs	4,493,000
Total Real Estate	77,353,000	[2]
Gross Amounts at Which Carried at Close of Period [Abstract]
Land	3,612,000
Building and Improvements	73,741,000
Total Real Estate	77,353,000	[2]
Accumulated Depreciation	5,606,000
Net investment in office and parking properties	71,747,000
Year Acquired	2012
Year constructed	2007
Additions [Abstract]
Balance at close of year	77,353,000	[2]
Accumulated Depreciation [Roll Forward]
Balance at close of year	5,606,000
ARIZONA | Hayden Ferry Lakeside III, IV and V [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0	[1]
Initial Cost to the Company [Abstract]
Land	9,046,000
Building and Improvements	8,561,000
Subsequent Capitalized Costs	1,384,000
Total Real Estate	18,991,000	[2]
Gross Amounts at Which Carried at Close of Period [Abstract]
Land	9,046,000
Building and Improvements	9,945,000
Total Real Estate	18,991,000	[2]
Accumulated Depreciation	437,000
Net investment in office and parking properties	18,554,000
Year Acquired	2012
Year constructed	2007
Additions [Abstract]
Balance at close of year	18,991,000	[2]
Accumulated Depreciation [Roll Forward]
Balance at close of year	437,000
ARIZONA | Squaw Peak Corporate Center [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0	[1]
Initial Cost to the Company [Abstract]
Land	5,800,000
Building and Improvements	35,144,000
Subsequent Capitalized Costs	7,222,000
Total Real Estate	48,166,000	[2]
Gross Amounts at Which Carried at Close of Period [Abstract]
Land	5,800,000
Building and Improvements	42,366,000
Total Real Estate	48,166,000	[2]
Accumulated Depreciation	12,522,000
Net investment in office and parking properties	35,644,000
Year Acquired	2004
Additions [Abstract]
Balance at close of year	48,166,000	[2]
Accumulated Depreciation [Roll Forward]
Balance at close of year	12,522,000
ARIZONA | Squaw Peak Corporate Center [Member] | Start [Member]
Gross Amounts at Which Carried at Close of Period [Abstract]
Year constructed	1999
ARIZONA | Squaw Peak Corporate Center [Member] | End [Member]
Gross Amounts at Which Carried at Close of Period [Abstract]
Year constructed	2000
ARIZONA | Tempe Gateway [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0	[1]
Initial Cost to the Company [Abstract]
Land	8,170,000
Building and Improvements	46,170,000
Subsequent Capitalized Costs	8,413,000
Total Real Estate	62,753,000	[2]
Gross Amounts at Which Carried at Close of Period [Abstract]
Land	8,170,000
Building and Improvements	54,583,000
Total Real Estate	62,753,000	[2]
Accumulated Depreciation	2,153,000
Net investment in office and parking properties	60,600,000
Year Acquired	2012
Year constructed	2009
Additions [Abstract]
Balance at close of year	62,753,000	[2]
Accumulated Depreciation [Roll Forward]
Balance at close of year	2,153,000
FLORIDA | Hillsboro Center V [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	9,121,000	[1]
Initial Cost to the Company [Abstract]
Land	1,325,000
Building and Improvements	12,249,000
Subsequent Capitalized Costs	4,782,000
Total Real Estate	18,356,000	[2]
Gross Amounts at Which Carried at Close of Period [Abstract]
Land	1,325,000
Building and Improvements	17,031,000
Total Real Estate	18,356,000	[2]
Accumulated Depreciation	7,234,000
Net investment in office and parking properties	11,122,000
Year Acquired	1998
Year constructed	1985
Additions [Abstract]
Balance at close of year	18,356,000	[2]
Accumulated Depreciation [Roll Forward]
Balance at close of year	7,234,000
FLORIDA | Hillsboro Center I-IV [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	6,219,000	[1]
Initial Cost to the Company [Abstract]
Land	1,129,000
Building and Improvements	7,734,000
Subsequent Capitalized Costs	2,910,000
Total Real Estate	11,773,000	[2]
Gross Amounts at Which Carried at Close of Period [Abstract]
Land	1,129,000
Building and Improvements	10,644,000
Total Real Estate	11,773,000	[2]
Accumulated Depreciation	4,556,000
Net investment in office and parking properties	7,217,000
Year Acquired	1998
Year constructed	1985
Additions [Abstract]
Balance at close of year	11,773,000	[2]
Accumulated Depreciation [Roll Forward]
Balance at close of year	4,556,000
FLORIDA | 245 Riverside [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	9,250,000	[1]
Initial Cost to the Company [Abstract]
Land	6,556,000
Building and Improvements	8,050,000
Subsequent Capitalized Costs	2,332,000
Total Real Estate	16,938,000	[2]
Gross Amounts at Which Carried at Close of Period [Abstract]
Land	6,556,000
Building and Improvements	10,382,000
Total Real Estate	16,938,000	[2]
Accumulated Depreciation	1,031,000
Net investment in office and parking properties	15,907,000
Year Acquired	2011
Year constructed	2003
Additions [Abstract]
Balance at close of year	16,938,000	[2]
Accumulated Depreciation [Roll Forward]
Balance at close of year	1,031,000
FLORIDA | Stein Mart Building [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	11,286,000	[1]
Initial Cost to the Company [Abstract]
Land	1,653,000
Building and Improvements	16,636,000
Subsequent Capitalized Costs	5,065,000
Total Real Estate	23,354,000	[2]
Gross Amounts at Which Carried at Close of Period [Abstract]
Land	1,653,000
Building and Improvements	21,701,000
Total Real Estate	23,354,000	[2]
Accumulated Depreciation	7,011,000
Net investment in office and parking properties	16,343,000
Year Acquired	2005
Year constructed	1985
Additions [Abstract]
Balance at close of year	23,354,000	[2]
Accumulated Depreciation [Roll Forward]
Balance at close of year	7,011,000
FLORIDA | Riverplace South [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0	[1]
Initial Cost to the Company [Abstract]
Land	2,316,000
Building and Improvements	5,412,000
Subsequent Capitalized Costs	3,003,000
Total Real Estate	10,731,000	[2]
Gross Amounts at Which Carried at Close of Period [Abstract]
Land	2,316,000
Building and Improvements	8,415,000
Total Real Estate	10,731,000	[2]
Accumulated Depreciation	3,269,000
Net investment in office and parking properties	7,462,000
Year Acquired	2005
Year constructed	1981
Additions [Abstract]
Balance at close of year	10,731,000	[2]
Accumulated Depreciation [Roll Forward]
Balance at close of year	3,269,000
FLORIDA | Westshore Corporate Center [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	14,312,000	[1]
Initial Cost to the Company [Abstract]
Land	0
Building and Improvements	17,532,000
Subsequent Capitalized Costs	3,258,000
Total Real Estate	20,790,000	[2]
Gross Amounts at Which Carried at Close of Period [Abstract]
Land	0
Building and Improvements	20,790,000
Total Real Estate	20,790,000	[2]
Accumulated Depreciation	1,185,000
Net investment in office and parking properties	19,605,000
Year Acquired	2012
Year constructed	1988
Additions [Abstract]
Balance at close of year	20,790,000	[2]
Accumulated Depreciation [Roll Forward]
Balance at close of year	1,185,000
FLORIDA | Lincoln Place [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	49,317,000	[1]
Initial Cost to the Company [Abstract]
Land	0
Building and Improvements	56,661,000
Subsequent Capitalized Costs	5,095,000
Total Real Estate	61,756,000	[2]
Gross Amounts at Which Carried at Close of Period [Abstract]
Land	0
Building and Improvements	61,756,000
Total Real Estate	61,756,000	[2]
Accumulated Depreciation	141,000
Net investment in office and parking properties	61,615,000
Year Acquired	2013
Year constructed	2002
Additions [Abstract]
Balance at close of year	61,756,000	[2]
Accumulated Depreciation [Roll Forward]
Balance at close of year	141,000
FLORIDA | Deerwood North [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	43,100,000	[1]
Initial Cost to the Company [Abstract]
Land	11,904,000
Building and Improvements	39,900,000
Subsequent Capitalized Costs	5,944,000
Total Real Estate	57,748,000	[2]
Gross Amounts at Which Carried at Close of Period [Abstract]
Land	11,904,000
Building and Improvements	45,844,000
Total Real Estate	57,748,000	[2]
Accumulated Depreciation	2,042,000
Net investment in office and parking properties	55,706,000
Year Acquired	2013
Year constructed	1999
Additions [Abstract]
Balance at close of year	57,748,000	[2]
Accumulated Depreciation [Roll Forward]
Balance at close of year	2,042,000
FLORIDA | Deerwood South [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	41,400,000	[1]
Initial Cost to the Company [Abstract]
Land	14,026,000
Building and Improvements	36,319,000
Subsequent Capitalized Costs	5,377,000
Total Real Estate	55,722,000	[2]
Gross Amounts at Which Carried at Close of Period [Abstract]
Land	14,026,000
Building and Improvements	41,696,000
Total Real Estate	55,722,000	[2]
Accumulated Depreciation	1,949,000
Net investment in office and parking properties	53,773,000
Year Acquired	2013
Year constructed	1999
Additions [Abstract]
Balance at close of year	55,722,000	[2]
Accumulated Depreciation [Roll Forward]
Balance at close of year	1,949,000
FLORIDA | Bank of America Center
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	33,875,000	[1]
Initial Cost to the Company [Abstract]
Land	8,882,000
Building and Improvements	38,598,000
Subsequent Capitalized Costs	8,321,000
Total Real Estate	55,801,000	[2]
Gross Amounts at Which Carried at Close of Period [Abstract]
Land	8,882,000
Building and Improvements	46,919,000
Total Real Estate	55,801,000	[2]
Accumulated Depreciation	5,480,000
Net investment in office and parking properties	50,321,000
Year Acquired	2011
Year constructed	1987
Additions [Abstract]
Balance at close of year	55,801,000	[2]
Accumulated Depreciation [Roll Forward]
Balance at close of year	5,480,000
FLORIDA | Citrus Center [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	21,601,000	[1]
Initial Cost to the Company [Abstract]
Land	4,000,000
Building and Improvements	26,712,000
Subsequent Capitalized Costs	7,575,000
Total Real Estate	38,287,000	[2]
Gross Amounts at Which Carried at Close of Period [Abstract]
Land	4,000,000
Building and Improvements	34,287,000
Total Real Estate	38,287,000	[2]
Accumulated Depreciation	11,463,000
Net investment in office and parking properties	26,824,000
Year Acquired	2003
Year constructed	1971
Additions [Abstract]
Balance at close of year	38,287,000	[2]
Accumulated Depreciation [Roll Forward]
Balance at close of year	11,463,000
FLORIDA | Corporate Center Four [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	36,000,000	[1]
Initial Cost to the Company [Abstract]
Land	0
Building and Improvements	31,775,000
Subsequent Capitalized Costs	8,689,000
Total Real Estate	40,464,000	[2]
Gross Amounts at Which Carried at Close of Period [Abstract]
Land	0
Building and Improvements	40,464,000
Total Real Estate	40,464,000	[2]
Accumulated Depreciation	4,779,000
Net investment in office and parking properties	35,685,000
Year Acquired	2011
Year constructed	2008
Additions [Abstract]
Balance at close of year	40,464,000	[2]
Accumulated Depreciation [Roll Forward]
Balance at close of year	4,779,000
FLORIDA | Cypress Center IV [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0	[1]
Initial Cost to the Company [Abstract]
Land	2,900,000
Building and Improvements	0
Subsequent Capitalized Costs	46,000
Total Real Estate	2,946,000	[2]
Gross Amounts at Which Carried at Close of Period [Abstract]
Land	2,900,000
Building and Improvements	46,000
Total Real Estate	2,946,000	[2]
Accumulated Depreciation	7,000
Net investment in office and parking properties	2,939,000
Year Acquired	2013
Additions [Abstract]
Balance at close of year	2,946,000	[2]
Accumulated Depreciation [Roll Forward]
Balance at close of year	7,000
FLORIDA | Cypress Center I - III [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0	[1]
Initial Cost to the Company [Abstract]
Land	4,710,000
Building and Improvements	12,180,000
Subsequent Capitalized Costs	4,754,000
Total Real Estate	21,644,000	[2]
Gross Amounts at Which Carried at Close of Period [Abstract]
Land	4,710,000
Building and Improvements	16,934,000
Total Real Estate	21,644,000	[2]
Accumulated Depreciation	3,297,000
Net investment in office and parking properties	18,347,000
Year Acquired	2011
Year constructed	1982
Additions [Abstract]
Balance at close of year	21,644,000	[2]
Accumulated Depreciation [Roll Forward]
Balance at close of year	3,297,000
FLORIDA | The Pointe [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	23,500,000	[1]
Initial Cost to the Company [Abstract]
Land	5,293,000
Building and Improvements	30,836,000
Subsequent Capitalized Costs	5,355,000
Total Real Estate	41,484,000	[2]
Gross Amounts at Which Carried at Close of Period [Abstract]
Land	5,293,000
Building and Improvements	36,191,000
Total Real Estate	41,484,000	[2]
Accumulated Depreciation	3,143,000
Net investment in office and parking properties	38,341,000
Year Acquired	2012
Year constructed	1982
Additions [Abstract]
Balance at close of year	41,484,000	[2]
Accumulated Depreciation [Roll Forward]
Balance at close of year	3,143,000
GEORGIA | 3344 Peachtree [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	84,739,000	[1]
Initial Cost to the Company [Abstract]
Land	7,472,000
Building and Improvements	127,583,000
Subsequent Capitalized Costs	11,355,000
Total Real Estate	146,410,000	[2]
Gross Amounts at Which Carried at Close of Period [Abstract]
Land	7,472,000
Building and Improvements	138,938,000
Total Real Estate	146,410,000	[2]
Accumulated Depreciation	13,772,000
Net investment in office and parking properties	132,638,000
Year Acquired	2011
Year constructed	2008
Additions [Abstract]
Balance at close of year	146,410,000	[2]
Accumulated Depreciation [Roll Forward]
Balance at close of year	13,772,000
GEORGIA | Two Ravinia Drive [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	22,100,000	[1]
Initial Cost to the Company [Abstract]
Land	3,187,000
Building and Improvements	32,948,000
Subsequent Capitalized Costs	9,147,000
Total Real Estate	45,282,000	[2]
Gross Amounts at Which Carried at Close of Period [Abstract]
Land	3,187,000
Building and Improvements	42,095,000
Total Real Estate	45,282,000	[2]
Accumulated Depreciation	5,024,000
Net investment in office and parking properties	40,258,000
Year Acquired	2011
Year constructed	1987
Additions [Abstract]
Balance at close of year	45,282,000	[2]
Accumulated Depreciation [Roll Forward]
Balance at close of year	5,024,000
GEORGIA | Peachtree Dunwoody Pavilion [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	26,118,000	[1]
Initial Cost to the Company [Abstract]
Land	9,373,000
Building and Improvements	24,579,000
Subsequent Capitalized Costs	8,059,000
Total Real Estate	42,011,000	[2]
Gross Amounts at Which Carried at Close of Period [Abstract]
Land	9,373,000
Building and Improvements	32,638,000
Total Real Estate	42,011,000	[2]
Accumulated Depreciation	9,840,000
Net investment in office and parking properties	32,171,000
Year Acquired	2003
Additions [Abstract]
Balance at close of year	42,011,000	[2]
Accumulated Depreciation [Roll Forward]
Balance at close of year	9,840,000
GEORGIA | Peachtree Dunwoody Pavilion [Member] | Start [Member]
Gross Amounts at Which Carried at Close of Period [Abstract]
Year constructed	1976
GEORGIA | Peachtree Dunwoody Pavilion [Member] | End [Member]
Gross Amounts at Which Carried at Close of Period [Abstract]
Year constructed	1980
GEORGIA | Capital City Plaza [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	32,860,000	[1]
Initial Cost to the Company [Abstract]
Land	3,625,000
Building and Improvements	57,218,000
Subsequent Capitalized Costs	6,121,000
Total Real Estate	66,964,000	[2]
Gross Amounts at Which Carried at Close of Period [Abstract]
Land	3,625,000
Building and Improvements	63,339,000
Total Real Estate	66,964,000	[2]
Accumulated Depreciation	16,056,000
Net investment in office and parking properties	50,908,000
Year Acquired	2004
Year constructed	1989
Additions [Abstract]
Balance at close of year	66,964,000	[2]
Accumulated Depreciation [Roll Forward]
Balance at close of year	16,056,000
GEORGIA | Tower Place 200 [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0	[1]
Initial Cost to the Company [Abstract]
Land	5,407,000
Building and Improvements	45,207,000
Subsequent Capitalized Costs	5,123,000
Total Real Estate	55,737,000	[2]
Gross Amounts at Which Carried at Close of Period [Abstract]
Land	5,407,000
Building and Improvements	50,330,000
Total Real Estate	55,737,000	[2]
Accumulated Depreciation	1,820,000
Net investment in office and parking properties	53,917,000
Year Acquired	2013
Year constructed	1998
Additions [Abstract]
Balance at close of year	55,737,000	[2]
Accumulated Depreciation [Roll Forward]
Balance at close of year	1,820,000
MISSISSIPPI | City Centre [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0	[1]
Initial Cost to the Company [Abstract]
Land	267,000
Building and Improvements	1,676,000
Subsequent Capitalized Costs	6,001,000
Total Real Estate	7,944,000	[2]
Gross Amounts at Which Carried at Close of Period [Abstract]
Land	267,000
Building and Improvements	7,677,000
Total Real Estate	7,944,000	[2]
Accumulated Depreciation	397,000
Net investment in office and parking properties	7,547,000
Year Acquired	1995
Additions [Abstract]
Balance at close of year	7,944,000	[2]
Accumulated Depreciation [Roll Forward]
Balance at close of year	397,000
MISSISSIPPI | City Centre [Member] | Second Major Renovation [Member]
Gross Amounts at Which Carried at Close of Period [Abstract]
Year constructed	2005	[3]
MISSISSIPPI | City Centre [Member] | First Major Renovation [Member]
Gross Amounts at Which Carried at Close of Period [Abstract]
Year constructed	1987	[3]
NORTH CAROLINA | Hearst Tower [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0	[1]
Initial Cost to the Company [Abstract]
Land	4,417,000
Building and Improvements	200,287,000
Subsequent Capitalized Costs	23,028,000
Total Real Estate	227,732,000	[2]
Gross Amounts at Which Carried at Close of Period [Abstract]
Land	4,417,000
Building and Improvements	223,315,000
Total Real Estate	227,732,000	[2]
Accumulated Depreciation	12,555,000
Net investment in office and parking properties	215,177,000
Year Acquired	2012
Year constructed	2002
Additions [Abstract]
Balance at close of year	227,732,000	[2]
Accumulated Depreciation [Roll Forward]
Balance at close of year	12,555,000
NORTH CAROLINA | 525 North Tryon [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0	[1]
Initial Cost to the Company [Abstract]
Land	5,108,000
Building and Improvements	34,103,000
Subsequent Capitalized Costs	7,361,000
Total Real Estate	46,572,000	[2]
Gross Amounts at Which Carried at Close of Period [Abstract]
Land	5,108,000
Building and Improvements	41,464,000
Total Real Estate	46,572,000	[2]
Accumulated Depreciation	2,355,000
Net investment in office and parking properties	44,217,000
Year Acquired	2012
Year constructed	1998
Additions [Abstract]
Balance at close of year	46,572,000	[2]
Accumulated Depreciation [Roll Forward]
Balance at close of year	2,355,000
NORTH CAROLINA | NASCAR Plaza [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0	[1]
Initial Cost to the Company [Abstract]
Land	0
Building and Improvements	76,790,000
Subsequent Capitalized Costs	11,052,000
Total Real Estate	87,842,000	[2]
Gross Amounts at Which Carried at Close of Period [Abstract]
Land	0
Building and Improvements	87,842,000
Total Real Estate	87,842,000	[2]
Accumulated Depreciation	3,174,000
Net investment in office and parking properties	84,668,000
Year Acquired	2012
Year constructed	2009
Additions [Abstract]
Balance at close of year	87,842,000	[2]
Accumulated Depreciation [Roll Forward]
Balance at close of year	3,174,000
PENNSYLVANIA | Two Liberty Place [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	90,200,000	[1]
Initial Cost to the Company [Abstract]
Land	32,587,000
Building and Improvements	97,593,000
Subsequent Capitalized Costs	17,659,000
Total Real Estate	147,839,000	[2]
Gross Amounts at Which Carried at Close of Period [Abstract]
Land	32,587,000
Building and Improvements	115,252,000
Total Real Estate	147,839,000	[2]
Accumulated Depreciation	13,161,000
Net investment in office and parking properties	134,678,000
Year Acquired	2011
Year constructed	1990
Additions [Abstract]
Balance at close of year	147,839,000	[2]
Accumulated Depreciation [Roll Forward]
Balance at close of year	13,161,000
TENNESSEE | Morgan Keegan Tower [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	9,211,000	[1]
Initial Cost to the Company [Abstract]
Land	0
Building and Improvements	18,588,000
Subsequent Capitalized Costs	4,400,000
Total Real Estate	22,988,000	[2]
Gross Amounts at Which Carried at Close of Period [Abstract]
Land	0
Building and Improvements	22,988,000
Total Real Estate	22,988,000	[2]
Accumulated Depreciation	1,515,000
Net investment in office and parking properties	21,473,000
Year Acquired	1997
Year constructed	1985
Additions [Abstract]
Balance at close of year	22,988,000	[2]
Accumulated Depreciation [Roll Forward]
Balance at close of year	1,515,000
TEXAS | 400 North Belt [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0	[1]
Initial Cost to the Company [Abstract]
Land	419,000
Building and Improvements	10,021,000
Subsequent Capitalized Costs	4,844,000
Total Real Estate	15,284,000	[2]
Gross Amounts at Which Carried at Close of Period [Abstract]
Land	419,000
Building and Improvements	14,865,000
Total Real Estate	15,284,000	[2]
Accumulated Depreciation	6,003,000
Net investment in office and parking properties	9,281,000
Year Acquired	1996
Year constructed	1982
Additions [Abstract]
Balance at close of year	15,284,000	[2]
Accumulated Depreciation [Roll Forward]
Balance at close of year	6,003,000
TEXAS | Honeywell [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0	[1]
Initial Cost to the Company [Abstract]
Land	856,000
Building and Improvements	15,235,000
Subsequent Capitalized Costs	4,591,000
Total Real Estate	20,682,000	[2]
Gross Amounts at Which Carried at Close of Period [Abstract]
Land	856,000
Building and Improvements	19,826,000
Total Real Estate	20,682,000	[2]
Accumulated Depreciation	7,785,000
Net investment in office and parking properties	12,897,000
Year Acquired	1997
Year constructed	1983
Additions [Abstract]
Balance at close of year	20,682,000	[2]
Accumulated Depreciation [Roll Forward]
Balance at close of year	7,785,000
TEXAS | Schlumberger [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0	[1]
Initial Cost to the Company [Abstract]
Land	1,013,000
Building and Improvements	11,102,000
Subsequent Capitalized Costs	4,757,000
Total Real Estate	16,872,000	[2]
Gross Amounts at Which Carried at Close of Period [Abstract]
Land	1,013,000
Building and Improvements	15,859,000
Total Real Estate	16,872,000	[2]
Accumulated Depreciation	8,176,000
Net investment in office and parking properties	8,696,000
Year Acquired	1998
Year constructed	1983
Additions [Abstract]
Balance at close of year	16,872,000	[2]
Accumulated Depreciation [Roll Forward]
Balance at close of year	8,176,000
TEXAS | One Commerce Green [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	17,412,000	[1]
Initial Cost to the Company [Abstract]
Land	489,000
Building and Improvements	37,307,000
Subsequent Capitalized Costs	5,811,000
Total Real Estate	43,607,000	[2]
Gross Amounts at Which Carried at Close of Period [Abstract]
Land	489,000
Building and Improvements	43,118,000
Total Real Estate	43,607,000	[2]
Accumulated Depreciation	19,335,000
Net investment in office and parking properties	24,272,000
Year Acquired	1998
Year constructed	1983
Additions [Abstract]
Balance at close of year	43,607,000	[2]
Accumulated Depreciation [Roll Forward]
Balance at close of year	19,335,000
TEXAS | Comerica Bank Building [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	12,437,000	[1]
Initial Cost to the Company [Abstract]
Land	1,921,000
Building and Improvements	21,222,000
Subsequent Capitalized Costs	4,716,000
Total Real Estate	27,859,000	[2]
Gross Amounts at Which Carried at Close of Period [Abstract]
Land	1,921,000
Building and Improvements	25,938,000
Total Real Estate	27,859,000	[2]
Accumulated Depreciation	10,624,000
Net investment in office and parking properties	17,235,000
Year Acquired	1998
Year constructed	1983
Additions [Abstract]
Balance at close of year	27,859,000	[2]
Accumulated Depreciation [Roll Forward]
Balance at close of year	10,624,000
TEXAS | 550 Greens Parkway [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0	[1]
Initial Cost to the Company [Abstract]
Land	1,006,000
Building and Improvements	8,061,000
Subsequent Capitalized Costs	460,000
Total Real Estate	9,527,000	[2]
Gross Amounts at Which Carried at Close of Period [Abstract]
Land	1,006,000
Building and Improvements	8,521,000
Total Real Estate	9,527,000	[2]
Accumulated Depreciation	2,874,000
Net investment in office and parking properties	6,653,000
Year Acquired	2001
Year constructed	1999
Additions [Abstract]
Balance at close of year	9,527,000	[2]
Accumulated Depreciation [Roll Forward]
Balance at close of year	2,874,000
TEXAS | 5300 Memorial Building [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	11,247,000	[1]
Initial Cost to the Company [Abstract]
Land	682,000
Building and Improvements	11,744,000
Subsequent Capitalized Costs	3,982,000
Total Real Estate	16,408,000	[2]
Gross Amounts at Which Carried at Close of Period [Abstract]
Land	682,000
Building and Improvements	15,726,000
Total Real Estate	16,408,000	[2]
Accumulated Depreciation	5,634,000
Net investment in office and parking properties	10,774,000
Year Acquired	2002
Year constructed	1982
Additions [Abstract]
Balance at close of year	16,408,000	[2]
Accumulated Depreciation [Roll Forward]
Balance at close of year	5,634,000
TEXAS | Town and Country [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	6,387,000	[1]
Initial Cost to the Company [Abstract]
Land	436,000
Building and Improvements	8,205,000
Subsequent Capitalized Costs	4,565,000
Total Real Estate	13,206,000	[2]
Gross Amounts at Which Carried at Close of Period [Abstract]
Land	436,000
Building and Improvements	12,770,000
Total Real Estate	13,206,000	[2]
Accumulated Depreciation	4,592,000
Net investment in office and parking properties	8,614,000
Year Acquired	2002
Year constructed	1982
Additions [Abstract]
Balance at close of year	13,206,000	[2]
Accumulated Depreciation [Roll Forward]
Balance at close of year	4,592,000
TEXAS | Phoenix Tower [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	80,000,000	[1]
Initial Cost to the Company [Abstract]
Land	9,191,000
Building and Improvements	98,147,000
Subsequent Capitalized Costs	9,867,000
Total Real Estate	117,205,000	[2]
Gross Amounts at Which Carried at Close of Period [Abstract]
Land	9,191,000
Building and Improvements	108,014,000
Total Real Estate	117,205,000	[2]
Accumulated Depreciation	4,558,000
Net investment in office and parking properties	112,647,000
Year Acquired	2012
Year constructed	1984
Additions [Abstract]
Balance at close of year	117,205,000	[2]
Accumulated Depreciation [Roll Forward]
Balance at close of year	4,558,000
TEXAS | Phoenix Tower [Member] | First Major Renovation [Member]
Gross Amounts at Which Carried at Close of Period [Abstract]
Year constructed	2011
TEXAS | CityWestPlace [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	211,030,000	[1]
Initial Cost to the Company [Abstract]
Land	56,785,000
Building and Improvements	305,992,000
Subsequent Capitalized Costs	30,551,000
Total Real Estate	393,328,000	[2]
Gross Amounts at Which Carried at Close of Period [Abstract]
Land	56,785,000
Building and Improvements	336,543,000
Total Real Estate	393,328,000	[2]
Accumulated Depreciation	471,000
Net investment in office and parking properties	392,857,000
Year Acquired	2013
Year constructed	2002
Additions [Abstract]
Balance at close of year	393,328,000	[2]
Accumulated Depreciation [Roll Forward]
Balance at close of year	471,000
TEXAS | San Felipe Plaza [Member]
Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	110,000,000	[1]
Initial Cost to the Company [Abstract]
Land	40,347,000
Building and Improvements	200,826,000
Subsequent Capitalized Costs	11,376,000
Total Real Estate	252,549,000	[2]
Gross Amounts at Which Carried at Close of Period [Abstract]
Land	40,347,000
Building and Improvements	212,202,000
Total Real Estate	252,549,000	[2]
Accumulated Depreciation	285,000
Net investment in office and parking properties	252,264,000
Year Acquired	2013
Year constructed	1984
Additions [Abstract]
Balance at close of year	252,549,000	[2]
Accumulated Depreciation [Roll Forward]
Balance at close of year	$ 285,000

[1] Encumbrances represent face amount of mortgage debt and exclude any premiums or discounts.

[2] Depreciation of buildings and improvements is calculated over lives ranging from the life of the lease to 40 years.

[3] The dates of major renovations.