INCOME TAXES - Components of Tax Provision by Jurisdiction (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current income tax expense/(benefit):
Federal	$ 16,400	$ (2,000)	$ (500)
State and local	2,100	(100)	(100)
Current income tax expense (benefit)	18,500	(2,100)	(600)
Deferred income tax expense/(benefit):
Federal	14,500	51,200	22,100
State and local	5,800	1,000	2,400
Deferred income tax expense (benefit)	20,271	52,178	24,547
Income tax expense	$ 38,859	$ 50,118	$ 23,935