Cash and Cash Equivalents, Restricted Cash and Marketable Securities (Details Textual) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	$ 83,576,000		$ 83,576,000		$ 81,223,000
Line Of Credit Facility, Maximum Borrowing Capacity	1,800,000,000		1,800,000,000
Available-for-sale Securities, Gross Unrealized Loss, Total		271,000		285,000
Available-for-sale Securities, Gross Unrealized Gain, Total	3,000		99,000
Unrealized Gain (Loss) on Securities Net of Tax	$ 2,000	$ (169,000)	$ 62,000	$ (178,000)