Long-Term Debt (Details) - Revolving credit facility - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Line of Credit Facility [Line Items]
Interest incurred	$ 449	$ 1,913	$ 2,295
Capitalized interest		534	563
Interest paid (net of capitalized interest)	$ 284	$ 1,169	$ 1,314
Weighted average interest rate		2.20%	2.20%