General (Details 4) (USD $)	Jun. 30, 2014	Dec. 31, 2013
Assets
Restricted Cash	$ 167,313,000	$ 236,696,000
Investments	171,355,000	208,313,000
Cash held in bank accounts by the Company, unrestricted	113,000,000	102,200,000
Cash held in bank accounts by the Company, restricted	95,400,000	108,400,000
Fair value measured on recurring basis | Level 1
Assets
Total assets held at fair value	2,078,000	1,129,000
Fair value measured on recurring basis | Level 1 | U.S. Government and agency securities
Assets
Investments	2,078,000	1,129,000
Fair value measured on recurring basis | Level 2
Assets
Total assets held at fair value	313,917,000	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	72,729,000	101,028,000
Restricted Cash	71,911,000	128,318,000
Fair value measured on recurring basis | Level 2 | Obligations of government-sponsored enterprises
Assets
Investments	8,707,000	8,440,000
Fair value measured on recurring basis | Level 2 | Corporate debt securities
Assets
Investments	159,420,000	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	46,982,000
Total liabilities held at fair value	46,982,000
Fair value measured on recurring basis | Total
Assets
Total assets held at fair value	315,995,000	437,659,000
Liabilities
Contingent consideration	46,982,000
Total liabilities held at fair value	46,982,000
Fair value measured on recurring basis | Total | Other than cash held in bank accounts by Company
Assets
Cash and Cash Equivalents	72,729,000	101,028,000
Restricted Cash	71,911,000	128,318,000
Fair value measured on recurring basis | Total | U.S. Government and agency securities
Assets
Investments	2,078,000	1,129,000
Fair value measured on recurring basis | Total | Obligations of government-sponsored enterprises
Assets
Investments	8,707,000	8,440,000
Fair value measured on recurring basis | Total | Corporate debt securities
Assets
Investments	159,420,000	198,594,000
Fair value measured on recurring basis | Total | Certificates of deposit
Assets
Investments	$ 1,150,000	$ 150,000