Intangible Assets, Goodwill and Other Assets (Schedule of Other Assets) (Details) - USD ($) $ in Thousands		Dec. 31, 2018		Jan. 01, 2018	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
CO2 volumetric production payments, net of amortization		$ 890			$ 2,175
Deferred marine charges, net	[1]	28,175			30,246
Contract Liabilities		72,241	[2]	$ 59,204	0	[2]
Other deferred costs and deposits		20,401			24,207
Other assets, net of amortization		$ 121,707		$ 115,832	$ 56,628

[1] See discussion of deferred charges on marine transportation assets in the Summary of Accounting Policies (Note 2)

[2] See Revenue Recognition (Note 3) for discussion on the circumstances that result in the recognition of contract assets.