Derivative Financial Instruments (Narrative) (Details) CAD in Millions	Dec. 31, 2016 USD ($)	Dec. 31, 2016 CAD	Jun. 30, 2016 derivative_instrument	Dec. 31, 2015 USD ($)	Dec. 31, 2015 CAD
Derivative [Line Items]
Interest rate derivative net receivable (payable), at fair value	$ 774,000			$ 3,000
Foreign currency exchange contracts
Derivative [Line Items]
Notional amount of foreign currency derivatives | CAD		CAD 9.0			CAD 7.3
Derivative, fair value, net receivable (payable)	100,000			400,000
Interest rate swap agreements | HBB
Derivative [Line Items]
Notional amount of foreign currency derivatives	20,000,000			20,000,000
Number of interest rate swap agreements | derivative_instrument			4
Interest rate derivative net receivable (payable), at fair value	800,000			(100,000)
Interest rate swap agreements | NACoal
Derivative [Line Items]
Notional amount of foreign currency derivatives	80,000,000			$ 100,000,000
Interest rate swap | NACoal
Derivative [Line Items]
Derivative, fair value, net receivable (payable)	$ (300,000)