Derivatives (Narrative) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended	3 Months Ended
	Dec. 31, 2013	Mar. 31, 2014 Commodity Derivatives [Member]		Mar. 31, 2013 Commodity Derivatives [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Accumulated OCI gain (loss), net of tax	$ 0	$ 0	[1]	$ (3,838)	[1]

[1] Net of taxes.