Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 35,489	$ 32,897	$ 85,993	$ 74,242
Other comprehensive income (loss):
Change in unrealized gain (loss) on valuation of interest rate swap agreements	(1,279)	930	(14,252)	(29,305)
Other comprehensive income (loss)	(1,279)	930	(14,252)	(29,305)
Comprehensive income (loss)	$ 34,210	$ 33,827	$ 71,741	$ 44,937

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income. 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 after tax of increase (decrease) in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss).

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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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