General (Details 4) (USD $)	Sep. 30, 2014	Dec. 31, 2013
Assets
Restricted Cash	$ 165,166,000	$ 236,696,000
Investments	201,424,000	208,313,000
Cash held in bank accounts by the Company, unrestricted	295,100,000	102,200,000
Cash held in bank accounts by the Company, restricted	88,700,000	108,400,000
Liabilities
Contingent consideration	51,981,000
Term Loan
Liabilities
Fair value of term loan	250,000,000
Fair value measured on recurring basis | Level 1
Assets
Total assets measured at fair value	2,393,000	1,129,000
Fair value measured on recurring basis | Level 1 | U.S. Government and agency securities
Assets
Investments	2,393,000	1,129,000
Fair value measured on recurring basis | Level 2
Assets
Total assets measured at fair value	348,653,000	436,530,000
Fair value measured on recurring basis | Level 2 | Other than cash held in bank accounts by Company
Assets
Cash and Cash Equivalents	73,194,000	101,028,000
Restricted Cash	76,428,000	128,318,000
Fair value measured on recurring basis | Level 2 | Obligations of government-sponsored enterprises
Assets
Investments	15,222,000	8,440,000
Fair value measured on recurring basis | Level 2 | Corporate debt securities
Assets
Investments	182,659,000	198,594,000
Fair value measured on recurring basis | Level 2 | Certificates of deposit
Assets
Investments	1,150,000	150,000
Fair value measured on recurring basis | Level 3
Liabilities
Contingent consideration	51,981,000
Total liabilities held at fair value	51,891,000
Fair value measured on recurring basis | Total
Assets
Total assets measured at fair value	351,046,000	437,659,000
Liabilities
Contingent consideration	51,981,000
Total liabilities held at fair value	51,891,000
Fair value measured on recurring basis | Total | Other than cash held in bank accounts by Company
Assets
Cash and Cash Equivalents	73,194,000	101,028,000
Restricted Cash	76,428,000	128,318,000
Fair value measured on recurring basis | Total | U.S. Government and agency securities
Assets
Investments	2,393,000	1,129,000
Fair value measured on recurring basis | Total | Obligations of government-sponsored enterprises
Assets
Investments	15,222,000	8,440,000
Fair value measured on recurring basis | Total | Corporate debt securities
Assets
Investments	182,659,000	198,594,000
Fair value measured on recurring basis | Total | Certificates of deposit
Assets
Investments	$ 1,150,000	$ 150,000