Long-Term Debt Credit Facility Available Borrowing Capacity (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014		Dec. 31, 2013		Jul. 23, 2014 Subsequent Event [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Amount Outstanding	$ 0		$ 0		$ 0
Letters of Credit Outstanding, Amount	808	[1]	808	[1]	808	[1]
Line of Credit Facility, Remaining Borrowing Capacity	$ 1,299,192		$ 1,299,192		$ 1,299,192

[1] (1) Letters of credit reduce the available borrowing capacity under the credit facility on a dollar-for-dollar basis.