Fair Value Measurements (Details 1) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Cash and Cash Equivalents, Fair Value Disclosure	$ 200,526	$ 137,266
Available-for-sale Securities, Fair Value Disclosure	312,888	201,521
Investments, Fair Value Disclosure	513,414	338,787
Accrued Liabilities, Fair Value Disclosure	0
Other Liabilities, Fair Value Disclosure	0	0
Liabilities, Fair Value Disclosure	0	0
Fair Value, Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Cash and Cash Equivalents, Fair Value Disclosure	2,463	0
Available-for-sale Securities, Fair Value Disclosure	5,475	552
Investments, Fair Value Disclosure	7,938	552
Accrued Liabilities, Fair Value Disclosure	0
Other Liabilities, Fair Value Disclosure	0	0
Liabilities, Fair Value Disclosure	0	0
Fair Value, Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Cash and Cash Equivalents, Fair Value Disclosure	0	0
Available-for-sale Securities, Fair Value Disclosure	0	0
Investments, Fair Value Disclosure	0	0
Accrued Liabilities, Fair Value Disclosure	12,453
Other Liabilities, Fair Value Disclosure	10,362	17,638
Liabilities, Fair Value Disclosure	22,815	17,638
Fair Value, Total
Fair Value, Balance Sheet Grouping, Financial Statement Captions
Cash and Cash Equivalents, Fair Value Disclosure	202,989	137,266
Available-for-sale Securities, Fair Value Disclosure	318,363	202,073
Investments, Fair Value Disclosure	521,352	339,339
Accrued Liabilities, Fair Value Disclosure	12,453
Other Liabilities, Fair Value Disclosure	10,362	17,638
Liabilities, Fair Value Disclosure	$ 22,815	$ 17,638