Fair Value Measurements (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Prepaid Expenses and Other Current Assets [Member]
Assets and liabilities measured at fair value on a recurring basis
Interest rate swaps, assets	$ 1,834	$ 0
Direct Financing Leases and Other Assets [Member]
Assets and liabilities measured at fair value on a recurring basis
Interest rate swaps, assets	6,162	9,333
Other Noncurrent Liabilities [Member]
Assets and liabilities measured at fair value on a recurring basis
Interest Rate Derivative Liabilities, at Fair Value	$ 141	$ 1,162