Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 575,667	$ (20,719)	$ 536,112
Available for sale securities:
Change in net unrealized (losses) gains	(1,770)	(3,285)	996
Less: reclassification adjustment for net losses (gains) included in net income	5,996	(273)	(1,204)
Net change (net of tax effect)	4,226	(3,558)	(208)
Gain on pension liability	1,569	2,768	906
Cash flow hedges:
Change in unrealized (losses) gains	(3,842)	6,046	(2,638)
Less: reclassification adjustment for net losses (gains) included in net income	699	(758)	1,763
Net change (net of tax effect)	(3,143)	5,288	(875)
Other comprehensive income (loss)	2,652	4,498	(177)
Comprehensive income (loss)	$ 578,319	$ (16,221)	$ 535,935

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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