Long-term Debt, Line of Credit and Derivatives - Financial covenants (Details)	3 Months Ended					6 Months Ended	12 Months Ended
	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2015
Debt Instrument [Line Items]
Debt instrument, covenant, fixed charge coverage ratio, maximum				1.25
Debt instrument, covenant, leverage ratio, maximum				3.75	4.00		3.25
Scenario, Forecast
Debt Instrument [Line Items]
Debt instrument, covenant, leverage ratio, maximum	2.75	3.00	3.25			2.50