Accounting Policies and Related Matters (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Accounting Policies [Abstract]
Loss (gain) on derivatives and financial instruments, net	$ 7,460	$ (736)	$ 14,633	$ (1,960)