SCHEDULE III - REAL ESTATE AND ACCUMULATED DEPRECIATION - Real Estate and Accumulated Depreciation (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Initial Cost to the Company
Total Real Estate	$ 3,332,021	$ 3,333,900	$ 2,548,036	$ 1,762,566
Gross Amount at Which Carried at Close of Period
Accumulated Depreciation	308,772	$ 309,629	$ 231,241	$ 199,849
Held-for-sale | Courvoisier Centre
Initial Cost to the Company
Encumbrances	0
Land	1,118
Building and Improvements	19,949
Subsequent Capitalized Costs	9,880
Total Real Estate	30,947
Gross Amount at Which Carried at Close of Period
Land	1,118
Building and Improvements	29,829
Accumulated Depreciation	12,785
Net Book Value of Real Estate	18,162
Held-for-sale | 5300 Memorial
Initial Cost to the Company
Encumbrances	0
Land	682
Building and Improvements	11,744
Subsequent Capitalized Costs	4,547
Total Real Estate	16,973
Gross Amount at Which Carried at Close of Period
Land	682
Building and Improvements	16,291
Accumulated Depreciation	6,911
Net Book Value of Real Estate	10,062
Held-for-sale | Town & Country
Initial Cost to the Company
Encumbrances	0
Land	436
Building and Improvements	8,205
Subsequent Capitalized Costs	5,333
Total Real Estate	13,974
Gross Amount at Which Carried at Close of Period
Land	436
Building and Improvements	13,538
Accumulated Depreciation	5,874
Net Book Value of Real Estate	8,100
Continuing Operations
Initial Cost to the Company
Encumbrances	1,218,458
Land	406,330
Building and Improvements	2,497,347
Subsequent Capitalized Costs	428,344
Total Real Estate	3,332,021
Gross Amount at Which Carried at Close of Period
Land	406,273
Building and Improvements	2,925,748
Accumulated Depreciation	308,772
Net Book Value of Real Estate	3,023,249
Continuing Operations | Corporate
Initial Cost to the Company
Encumbrances	0
Land	0
Building and Improvements	29
Subsequent Capitalized Costs	6,007
Total Real Estate	6,036
Gross Amount at Which Carried at Close of Period
Land	0
Building and Improvements	6,036
Accumulated Depreciation	1,380
Net Book Value of Real Estate	4,656
Continuing Operations | Arizona | Hayden Ferry Lakeside I
Initial Cost to the Company
Encumbrances	21,536
Land	2,871
Building and Improvements	30,428
Subsequent Capitalized Costs	6,918
Total Real Estate	40,217
Gross Amount at Which Carried at Close of Period
Land	2,871
Building and Improvements	37,346
Accumulated Depreciation	7,553
Net Book Value of Real Estate	32,664
Continuing Operations | Arizona | Hayden Ferry Lakeside II
Initial Cost to the Company
Encumbrances	46,064
Land	3,612
Building and Improvements	69,246
Subsequent Capitalized Costs	7,746
Total Real Estate	80,604
Gross Amount at Which Carried at Close of Period
Land	3,612
Building and Improvements	76,992
Accumulated Depreciation	10,719
Net Book Value of Real Estate	69,885
Continuing Operations | Arizona | Hayden Ferry Lakeside III
Initial Cost to the Company
Encumbrances	31,271
Land	4,024
Building and Improvements	28,383
Subsequent Capitalized Costs	24,326
Total Real Estate	56,733
Gross Amount at Which Carried at Close of Period
Land	4,024
Building and Improvements	52,709
Accumulated Depreciation	218
Net Book Value of Real Estate	56,515
Continuing Operations | Arizona | Hayden Ferry Lakeside IV and V
Initial Cost to the Company
Encumbrances	0
Land	5,023
Building and Improvements	8,561
Subsequent Capitalized Costs	1,626
Total Real Estate	15,210
Gross Amount at Which Carried at Close of Period
Land	5,023
Building and Improvements	10,187
Accumulated Depreciation	1,162
Net Book Value of Real Estate	14,048
Continuing Operations | Arizona | Tempe Gateway
Initial Cost to the Company
Encumbrances	0
Land	6,970
Building and Improvements	45,232
Subsequent Capitalized Costs	10,718
Total Real Estate	62,920
Gross Amount at Which Carried at Close of Period
Land	6,970
Building and Improvements	55,950
Accumulated Depreciation	7,204
Net Book Value of Real Estate	55,716
Continuing Operations | Florida | Stein Mart Building
Initial Cost to the Company
Encumbrances	10,778
Land	1,653
Building and Improvements	16,636
Subsequent Capitalized Costs	7,256
Total Real Estate	25,545
Gross Amount at Which Carried at Close of Period
Land	1,653
Building and Improvements	23,892
Accumulated Depreciation	8,436
Net Book Value of Real Estate	17,109
Continuing Operations | Florida | Lincoln Place
Initial Cost to the Company
Encumbrances	48,030
Land	0
Building and Improvements	56,997
Subsequent Capitalized Costs	4,988
Total Real Estate	61,985
Gross Amount at Which Carried at Close of Period
Land	0
Building and Improvements	61,985
Accumulated Depreciation	3,842
Net Book Value of Real Estate	58,143
Continuing Operations | Florida | Deerwood North
Initial Cost to the Company
Encumbrances	84,500
Land	11,904
Building and Improvements	39,900
Subsequent Capitalized Costs	6,481
Total Real Estate	58,285
Gross Amount at Which Carried at Close of Period
Land	11,904
Building and Improvements	46,381
Accumulated Depreciation	6,918
Net Book Value of Real Estate	51,367
Continuing Operations | Florida | Deerwood South
Initial Cost to the Company
Encumbrances	0
Land	14,026
Building and Improvements	36,319
Subsequent Capitalized Costs	7,244
Total Real Estate	57,589
Gross Amount at Which Carried at Close of Period
Land	14,026
Building and Improvements	43,563
Accumulated Depreciation	6,206
Net Book Value of Real Estate	51,383
Continuing Operations | Florida | Bank of America Center
Initial Cost to the Company
Encumbrances	0
Land	8,882
Building and Improvements	38,595
Subsequent Capitalized Costs	11,655
Total Real Estate	59,132
Gross Amount at Which Carried at Close of Period
Land	8,882
Building and Improvements	50,250
Accumulated Depreciation	9,908
Net Book Value of Real Estate	49,224
Continuing Operations | Florida | Citrus Center
Initial Cost to the Company
Encumbrances	20,645
Land	4,000
Building and Improvements	26,712
Subsequent Capitalized Costs	11,904
Total Real Estate	42,616
Gross Amount at Which Carried at Close of Period
Land	4,000
Building and Improvements	38,616
Accumulated Depreciation	14,247
Net Book Value of Real Estate	28,369
Continuing Operations | Florida | Corporate Center I
Initial Cost to the Company
Encumbrances	0
Land	0
Building and Improvements	77,997
Subsequent Capitalized Costs	7,319
Total Real Estate	85,316
Gross Amount at Which Carried at Close of Period
Land	0
Building and Improvements	85,316
Accumulated Depreciation	3,181
Net Book Value of Real Estate	82,135
Continuing Operations | Florida | Corporate Center II
Initial Cost to the Company
Encumbrances	0
Land	0
Building and Improvements	58,493
Subsequent Capitalized Costs	4,738
Total Real Estate	63,231
Gross Amount at Which Carried at Close of Period
Land	0
Building and Improvements	63,231
Accumulated Depreciation	2,483
Net Book Value of Real Estate	60,748
Continuing Operations | Florida | Corporate Center III
Initial Cost to the Company
Encumbrances	0
Land	0
Building and Improvements	63,633
Subsequent Capitalized Costs	4,463
Total Real Estate	68,096
Gross Amount at Which Carried at Close of Period
Land	0
Building and Improvements	68,096
Accumulated Depreciation	2,512
Net Book Value of Real Estate	65,584
Continuing Operations | Florida | Corporate Center IV
Initial Cost to the Company
Encumbrances	35,491
Land	0
Building and Improvements	31,773
Subsequent Capitalized Costs	8,755
Total Real Estate	40,528
Gross Amount at Which Carried at Close of Period
Land	0
Building and Improvements	40,528
Accumulated Depreciation	8,545
Net Book Value of Real Estate	31,983
Continuing Operations | Florida | Corporate Center VI
Initial Cost to the Company
Encumbrances	0
Land	4,901
Building and Improvements	0
Subsequent Capitalized Costs	0
Total Real Estate	4,901
Gross Amount at Which Carried at Close of Period
Land	4,901
Building and Improvements	0
Accumulated Depreciation	0
Net Book Value of Real Estate	4,901
Continuing Operations | Florida | Courvoisier Centre
Initial Cost to the Company
Encumbrances	0
Land	48,407
Building and Improvements	74,738
Subsequent Capitalized Costs	11,098
Total Real Estate	134,243
Gross Amount at Which Carried at Close of Period
Land	48,407
Building and Improvements	85,836
Accumulated Depreciation	5,983
Net Book Value of Real Estate	128,260
Continuing Operations | Florida | Harborview Plaza
Initial Cost to the Company
Encumbrances	0
Land	8,560
Building and Improvements	33,263
Subsequent Capitalized Costs	2,781
Total Real Estate	44,604
Gross Amount at Which Carried at Close of Period
Land	8,560
Building and Improvements	36,044
Accumulated Depreciation	441
Net Book Value of Real Estate	44,163
Continuing Operations | Florida | The Pointe
Initial Cost to the Company
Encumbrances	23,364
Land	5,293
Building and Improvements	30,834
Subsequent Capitalized Costs	6,188
Total Real Estate	42,315
Gross Amount at Which Carried at Close of Period
Land	5,293
Building and Improvements	37,022
Accumulated Depreciation	6,431
Net Book Value of Real Estate	35,884
Continuing Operations | Florida | JTB Center
Initial Cost to the Company
Encumbrances	0
Land	5,376
Building and Improvements	21,494
Subsequent Capitalized Costs	4,722
Total Real Estate	31,592
Gross Amount at Which Carried at Close of Period
Land	5,376
Building and Improvements	26,216
Accumulated Depreciation	2,652
Net Book Value of Real Estate	28,940
Continuing Operations | Florida | One Orlando Centre
Initial Cost to the Company
Encumbrances	54,000
Land	9,828
Building and Improvements	37,555
Subsequent Capitalized Costs	9,316
Total Real Estate	56,699
Gross Amount at Which Carried at Close of Period
Land	9,828
Building and Improvements	46,871
Accumulated Depreciation	3,629
Net Book Value of Real Estate	53,070
Continuing Operations | Georgia | 3344 Peachtree
Initial Cost to the Company
Encumbrances	80,986
Land	7,472
Building and Improvements	127,579
Subsequent Capitalized Costs	12,853
Total Real Estate	147,904
Gross Amount at Which Carried at Close of Period
Land	7,472
Building and Improvements	140,432
Accumulated Depreciation	23,304
Net Book Value of Real Estate	124,600
Continuing Operations | Georgia | One Buckhead Plaza
Initial Cost to the Company
Encumbrances	0
Land	20,031
Building and Improvements	125,204
Subsequent Capitalized Costs	8,644
Total Real Estate	153,879
Gross Amount at Which Carried at Close of Period
Land	20,031
Building and Improvements	133,848
Accumulated Depreciation	4,392
Net Book Value of Real Estate	149,487
Continuing Operations | Georgia | Two Buckhead Plaza
Initial Cost to the Company
Encumbrances	52,000
Land	12,934
Building and Improvements	66,249
Subsequent Capitalized Costs	4,048
Total Real Estate	83,231
Gross Amount at Which Carried at Close of Period
Land	12,877
Building and Improvements	70,354
Accumulated Depreciation	711
Net Book Value of Real Estate	82,520
Continuing Operations | Georgia | 3350 Peachtree
Initial Cost to the Company
Encumbrances	0
Land	3,625
Building and Improvements	57,218
Subsequent Capitalized Costs	20,607
Total Real Estate	81,450
Gross Amount at Which Carried at Close of Period
Land	3,625
Building and Improvements	77,825
Accumulated Depreciation	21,213
Net Book Value of Real Estate	60,237
Continuing Operations | Georgia | 3348 Peachtree
Initial Cost to the Company
Encumbrances	0
Land	5,407
Building and Improvements	45,207
Subsequent Capitalized Costs	9,590
Total Real Estate	60,204
Gross Amount at Which Carried at Close of Period
Land	5,407
Building and Improvements	54,797
Accumulated Depreciation	5,745
Net Book Value of Real Estate	54,459
Continuing Operations | Georgia | The Forum at West Paces
Initial Cost to the Company
Encumbrances	0
Land	3,314
Building and Improvements	38,577
Subsequent Capitalized Costs	7,857
Total Real Estate	49,748
Gross Amount at Which Carried at Close of Period
Land	3,314
Building and Improvements	46,434
Accumulated Depreciation	2,087
Net Book Value of Real Estate	47,661
Continuing Operations | North Carolina | Hearst Tower
Initial Cost to the Company
Encumbrances	0
Land	4,417
Building and Improvements	200,287
Subsequent Capitalized Costs	35,070
Total Real Estate	239,774
Gross Amount at Which Carried at Close of Period
Land	4,417
Building and Improvements	235,357
Accumulated Depreciation	28,938
Net Book Value of Real Estate	210,836
Continuing Operations | North Carolina | NASCAR Plaza
Initial Cost to the Company
Encumbrances	0
Land	0
Building and Improvements	76,874
Subsequent Capitalized Costs	14,425
Total Real Estate	91,299
Gross Amount at Which Carried at Close of Period
Land	0
Building and Improvements	91,299
Accumulated Depreciation	9,830
Net Book Value of Real Estate	81,469
Continuing Operations | Pennsylvania | Two Liberty Place
Initial Cost to the Company
Encumbrances	89,567
Land	32,587
Building and Improvements	97,585
Subsequent Capitalized Costs	18,020
Total Real Estate	148,192
Gross Amount at Which Carried at Close of Period
Land	32,587
Building and Improvements	115,605
Accumulated Depreciation	23,323
Net Book Value of Real Estate	124,869
Continuing Operations | Texas | Phoenix Tower
Initial Cost to the Company
Encumbrances	78,555
Land	9,191
Building and Improvements	98,183
Subsequent Capitalized Costs	14,768
Total Real Estate	122,142
Gross Amount at Which Carried at Close of Period
Land	9,191
Building and Improvements	112,951
Accumulated Depreciation	13,887
Net Book Value of Real Estate	108,255
Continuing Operations | Texas | CityWestPlace
Initial Cost to the Company
Encumbrances	204,794
Land	56,785
Building and Improvements	295,869
Subsequent Capitalized Costs	73,018
Total Real Estate	425,672
Gross Amount at Which Carried at Close of Period
Land	56,785
Building and Improvements	368,887
Accumulated Depreciation	34,906
Net Book Value of Real Estate	390,766
Continuing Operations | Texas | San Felipe Plaza
Initial Cost to the Company
Encumbrances	107,877
Land	40,347
Building and Improvements	206,510
Subsequent Capitalized Costs	22,409
Total Real Estate	269,266
Gross Amount at Which Carried at Close of Period
Land	40,347
Building and Improvements	228,919
Accumulated Depreciation	16,807
Net Book Value of Real Estate	252,459
Continuing Operations | Texas | One Congress Plaza
Initial Cost to the Company
Encumbrances	128,000
Land	33,245
Building and Improvements	118,370
Subsequent Capitalized Costs	12,447
Total Real Estate	164,062
Gross Amount at Which Carried at Close of Period
Land	33,245
Building and Improvements	130,817
Accumulated Depreciation	5,389
Net Book Value of Real Estate	158,673
Continuing Operations | Texas | San Jacinto Center
Initial Cost to the Company
Encumbrances	101,000
Land	31,645
Building and Improvements	116,817
Subsequent Capitalized Costs	8,339
Total Real Estate	156,801
Gross Amount at Which Carried at Close of Period
Land	31,645
Building and Improvements	125,156
Accumulated Depreciation	4,590
Net Book Value of Real Estate	$ 152,211