Cash, Cash Equivalents and Available for Sale Securities (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
Cash, Cash Equivalents and Available for Sale Securities [Abstract]
Cash	$ 372,300,000	$ 330,800,000
Investments in cash equivalents	6,000,000	45,900,000
Restricted cash	1,491,000	1,574,000
Restricted cash outstanding, letters of credit used for collateral	1,000,000
Restricted cash guaranteed, investment certificate for collateral	200,000	200,000
Restricted cash and cash equivalents, foreign tender	$ 300,000	$ 400,000