CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities
Net income	$ 5,732,573	$ 2,777,313	$ 7,925,494
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	7,472,341	7,421,268	5,836,933
Amortization of debt issuance costs	0	41,672	125,016
Deferred income tax benefit	(888,977)	(536,057)	0
Provision for doubtful accounts	0	42,553	0
Unrealized (gain) loss on put/call option	(960,000)	297,000	0
Compensation expense relating to stock and stock option grants	803,577	521,019	407,668
Net loss (gain) on disposal of fixed assets	117,969	(314,381)	32,566
Foreign currency transaction adjustment	6,685	(172,130)	420,641
Profit sharing and equity in earnings of OC-BVI	(174,377)	(463,359)	(399,668)
Impairment loss on long-lived assets	1,656,362	2,000,000	0
Impairment of goodwill	1,400,000	1,750,000	0
Impairment of investment in OC-BVI	0	925,000	1,060,000
Change in:
Accounts receivable and costs and estimated earnings in excess of billings	1,370,128	(5,910,009)	3,402,728
Inventory	(217,028)	(622,724)	(732,588)
Prepaid expenses and other assets	(3,083,708)	204,642	299,130
Accounts payable and other liabilities and billings in excess of costs and estimated earnings - construction project	408,749	(138,455)	(1,058,134)
Net cash provided by operating activities	13,644,294	7,823,352	17,319,786
Cash flows from investing activities
Purchase of certificate of deposit	0	0	(5,637,538)
Maturity of certificate of deposit	0	5,637,538	5,000,000
Additions to property, plant and equipment and construction in progress	(4,576,717)	(3,462,150)	(3,113,565)
Proceeds from sale of equipment	22,427	547,332	10,160
Distribution of earnings from OC-BVI	1,477,125	0	0
Acquisition of Aerex, net of cash acquired	0	(7,742,853)	0
Collections on loans receivable	1,633,588	1,841,851	1,726,310
Release of restricted cash balance	0	398,744	(42,716)
Net cash used in investing activities	(1,443,577)	(2,779,538)	(2,057,349)
Cash flows from financing activities
Dividends paid to common shareholders	(4,464,712)	(4,433,539)	(4,417,534)
Dividends paid to non-controlling interests	0	(182,663)	(201,473)
Dividends paid to preferred shareholders	(11,213)	(11,831)	(11,881)
Issuance (repurchase) of redeemable preferred stock	(9,719)	(14,054)	(6,014)
Proceeds received from exercise of stock options	17,777	568,849	456,763
Issuance (repayment) of note payable to related party	(490,000)	490,000	0
Issuance of note payable to related party	686,000	0	0
Repayments of demand loan payable	0	(7,000,000)	(2,000,000)
Net cash used in financing activities	(4,271,867)	(10,583,238)	(6,180,139)
Effect of exchange rate changes on cash	0	806	(3,253)
Net increase (decrease) in cash and cash equivalents	7,928,850	(5,538,618)	9,079,045
Cash and cash equivalents at beginning of period	39,254,116	44,792,734	35,713,689
Cash and cash equivalents at end of period	$ 47,182,966	$ 39,254,116	$ 44,792,734