Nature of Operations and Summary of Significant Accounting Policies--Inventories (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Accounting Policies [Abstract]
Inventory write-down	$ 0	$ 0	$ 602
Equipment inventory	13,657	8,047
Oil and natural gas product	3,186	3,175
Inventory valuation allowance	706	712
Inventories, net	$ 16,137	$ 10,510