Schedule III - Real Estate and Accumulated Depreciation and Amortization Part 5 (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Schedule Of Investments In Real Estate [Line Items]
Total Investment in Real Estate	$ 782,166	$ 783,233	$ 595,959	$ 570,275
Accumulated Depreciation And Amortization Description [Member]
Schedule Of Investments In Real Estate [Line Items]
Initial Cost of Leasehold or Acquisition Investment to Company	720,099
Cost Capitalized Subsequent to Initial Investment	62,067
Land	474,232
Building and Improvements	307,934
Total Investment in Real Estate	782,166
Accumulated Depreciation and Amortization	120,576
CONNECTICUT | Accumulated Depreciation And Amortization Description [Member] | Farmington One [Member]
Schedule Of Investments In Real Estate [Line Items]
Initial Cost of Leasehold or Acquisition Investment to Company	466
Land	303
Building and Improvements	163
Total Investment in Real Estate	466
Accumulated Depreciation and Amortization	$ 79
Date of Initial Leasehold or Acquisition Investment	2004
CONNECTICUT | Accumulated Depreciation And Amortization Description [Member] | Franklin One [Member]
Schedule Of Investments In Real Estate [Line Items]
Initial Cost of Leasehold or Acquisition Investment to Company	$ 51
Cost Capitalized Subsequent to Initial Investment	447
Land	20
Building and Improvements	478
Total Investment in Real Estate	498
Accumulated Depreciation and Amortization	$ 257
Date of Initial Leasehold or Acquisition Investment	1982
CONNECTICUT | Accumulated Depreciation And Amortization Description [Member] | Hartford One [Member]
Schedule Of Investments In Real Estate [Line Items]
Initial Cost of Leasehold or Acquisition Investment to Company	$ 571
Land	371
Building and Improvements	200
Total Investment in Real Estate	571
Accumulated Depreciation and Amortization	$ 97
Date of Initial Leasehold or Acquisition Investment	2004
CONNECTICUT | Accumulated Depreciation And Amortization Description [Member] | Hartford Two [Member]
Schedule Of Investments In Real Estate [Line Items]
Initial Cost of Leasehold or Acquisition Investment to Company	$ 665
Land	432
Building and Improvements	233
Total Investment in Real Estate	665
Accumulated Depreciation and Amortization	$ 113
Date of Initial Leasehold or Acquisition Investment	2004
CONNECTICUT | Accumulated Depreciation And Amortization Description [Member] | Manchester One [Member]
Schedule Of Investments In Real Estate [Line Items]
Initial Cost of Leasehold or Acquisition Investment to Company	$ 110
Cost Capitalized Subsequent to Initial Investment	323
Land	50
Building and Improvements	383
Total Investment in Real Estate	433
Accumulated Depreciation and Amortization	$ 147
Date of Initial Leasehold or Acquisition Investment	1987
CONNECTICUT | Accumulated Depreciation And Amortization Description [Member] | Meriden One [Member]
Schedule Of Investments In Real Estate [Line Items]
Initial Cost of Leasehold or Acquisition Investment to Company	$ 208
Cost Capitalized Subsequent to Initial Investment	339
Land	84
Building and Improvements	463
Total Investment in Real Estate	547
Accumulated Depreciation and Amortization	$ 229
Date of Initial Leasehold or Acquisition Investment	1982
CONNECTICUT | Accumulated Depreciation And Amortization Description [Member] | Meriden Two [Member]
Schedule Of Investments In Real Estate [Line Items]
Initial Cost of Leasehold or Acquisition Investment to Company	$ 1,532
Land	989
Building and Improvements	543
Total Investment in Real Estate	1,532
Accumulated Depreciation and Amortization	$ 269
Date of Initial Leasehold or Acquisition Investment	2004
CONNECTICUT | Accumulated Depreciation And Amortization Description [Member] | Middletown One [Member]
Schedule Of Investments In Real Estate [Line Items]
Initial Cost of Leasehold or Acquisition Investment to Company	$ 132
Cost Capitalized Subsequent to Initial Investment	564
Land	131
Building and Improvements	565
Total Investment in Real Estate	696
Accumulated Depreciation and Amortization	$ 242
Date of Initial Leasehold or Acquisition Investment	1987
CONNECTICUT | Accumulated Depreciation And Amortization Description [Member] | Middletown Two [Member]
Schedule Of Investments In Real Estate [Line Items]
Initial Cost of Leasehold or Acquisition Investment to Company	$ 1,039
Land	675
Building and Improvements	364
Total Investment in Real Estate	1,039
Accumulated Depreciation and Amortization	$ 177
Date of Initial Leasehold or Acquisition Investment	2004
CONNECTICUT | Accumulated Depreciation And Amortization Description [Member] | Milford One [Member]
Schedule Of Investments In Real Estate [Line Items]
Initial Cost of Leasehold or Acquisition Investment to Company	$ 293
Cost Capitalized Subsequent to Initial Investment	45
Land	191
Building and Improvements	147
Total Investment in Real Estate	338
Accumulated Depreciation and Amortization	$ 120
Date of Initial Leasehold or Acquisition Investment	1985
CONNECTICUT | Accumulated Depreciation And Amortization Description [Member] | Milford Two [Member]
Schedule Of Investments In Real Estate [Line Items]
Initial Cost of Leasehold or Acquisition Investment to Company	$ 57
Cost Capitalized Subsequent to Initial Investment	295
Land	30
Building and Improvements	322
Total Investment in Real Estate	352
Accumulated Depreciation and Amortization	$ 103
Date of Initial Leasehold or Acquisition Investment	1985
CONNECTICUT | Accumulated Depreciation And Amortization Description [Member] | Montville [Member]
Schedule Of Investments In Real Estate [Line Items]
Initial Cost of Leasehold or Acquisition Investment to Company	$ 57
Cost Capitalized Subsequent to Initial Investment	332
Land	24
Building and Improvements	365
Total Investment in Real Estate	389
Accumulated Depreciation and Amortization	$ 146
Date of Initial Leasehold or Acquisition Investment	1982
CONNECTICUT | Accumulated Depreciation And Amortization Description [Member] | New Britain One [Member]
Schedule Of Investments In Real Estate [Line Items]
Initial Cost of Leasehold or Acquisition Investment to Company	$ 391
Land	254
Building and Improvements	137
Total Investment in Real Estate	391
Accumulated Depreciation and Amortization	$ 67
Date of Initial Leasehold or Acquisition Investment	2004
CONNECTICUT | Accumulated Depreciation And Amortization Description [Member] | New Haven One [Member]
Schedule Of Investments In Real Estate [Line Items]
Initial Cost of Leasehold or Acquisition Investment to Company	$ 217
Cost Capitalized Subsequent to Initial Investment	297
Land	141
Building and Improvements	373
Total Investment in Real Estate	514
Accumulated Depreciation and Amortization	$ 135
Date of Initial Leasehold or Acquisition Investment	1985
CONNECTICUT | Accumulated Depreciation And Amortization Description [Member] | New Haven Two [Member]
Schedule Of Investments In Real Estate [Line Items]
Initial Cost of Leasehold or Acquisition Investment to Company	$ 539
Cost Capitalized Subsequent to Initial Investment	454
Land	351
Building and Improvements	642
Total Investment in Real Estate	993
Accumulated Depreciation and Amortization	$ 373
Date of Initial Leasehold or Acquisition Investment	1985
CONNECTICUT | Accumulated Depreciation And Amortization Description [Member] | New Haven Three [Member]
Schedule Of Investments In Real Estate [Line Items]
Initial Cost of Leasehold or Acquisition Investment to Company	$ 1,414
Cost Capitalized Subsequent to Initial Investment	(275)
Land	569
Building and Improvements	570
Total Investment in Real Estate	1,139
Accumulated Depreciation and Amortization	$ 99
Date of Initial Leasehold or Acquisition Investment	1985
CONNECTICUT | Accumulated Depreciation And Amortization Description [Member] | Newington One [Member]
Schedule Of Investments In Real Estate [Line Items]
Initial Cost of Leasehold or Acquisition Investment to Company	$ 954
Land	620
Building and Improvements	334
Total Investment in Real Estate	954
Accumulated Depreciation and Amortization	$ 162
Date of Initial Leasehold or Acquisition Investment	2004