Held for Sale (Assets and Liabilities of Properties Held for Sale) (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Assets Held for Sale:
Assets	$ 1	$ 14
Liabilities Held for Sale:
Liabilities	157	5,295
Disposal Group, Held-for-sale, Not Discontinued Operations
Assets Held for Sale:
Property and equipment	7,029	6,301
Other intangible assets	1,681	1,681
Assets	14,599	30,377
Liabilities Held for Sale:
Other liabilities	0	103
Liabilities	0	103
Real Estate | Disposal Group, Held-for-sale, Not Discontinued Operations
Assets Held for Sale:
Property and equipment	5,740	19,931
Timber Properties | Disposal Group, Held-for-sale, Not Discontinued Operations
Assets Held for Sale:
Property and equipment	0	1,682
Oil and Gas Properties | Disposal Group, Held-for-sale, Not Discontinued Operations
Assets Held for Sale:
Property and equipment	$ 149	$ 782