Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statement of Comprehensive Income [Abstract]
NET INCOME	$ 32,200us-gaap_ProfitLoss	$ 6,983us-gaap_ProfitLoss	$ 5,535us-gaap_ProfitLoss
Other comprehensive income (loss):
Defined benefit pension plan net gain (loss) arising during the period	(2,570)	2,143	1,240
Other comprehensive income (loss)	(2,570)	2,143	1,240
COMPREHENSIVE INCOME	29,630	9,126	6,775
Less: Net income attributable to noncontrolling interests	(313)	(37)	(70)
COMPREHENSIVE INCOME ATTRIBUTABLE TO COMMON STOCKHOLDERS	$ 29,317us-gaap_ComprehensiveIncomeNetOfTax	$ 9,089us-gaap_ComprehensiveIncomeNetOfTax	$ 6,705us-gaap_ComprehensiveIncomeNetOfTax

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

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Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income (loss) and other comprehensive income (loss), attributable to noncontrolling interests. Excludes changes in equity resulting from investments by owners and distributions to owners.

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Amount after tax and reclassification adjustments of other comprehensive income (loss).

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Amount before tax of reclassification adjustment from accumulated other comprehensive (income) loss related to net period benefit cost (credit) for pension and other postretirement defined benefit plans.

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The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.

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