Marketable Securities - Schedule of Maturities (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Less than 1 Year	$ 18,305
1-5 Years	80,794
5-10 Years	9,414
5-10 Years	6,467
Fair Value	114,980	$ 79,738
Equity securities
Schedule of Available-for-sale Securities [Line Items]
Less than 1 Year	4,033
1-5 Years	0
5-10 Years	0
5-10 Years	0
Fair Value	4,033	3,525
Corporate bonds
Schedule of Available-for-sale Securities [Line Items]
Less than 1 Year	11,933
1-5 Years	39,325
5-10 Years	5,655
5-10 Years	435
Fair Value	57,348	42,139
Government securities - U.S.
Schedule of Available-for-sale Securities [Line Items]
Less than 1 Year	2,258
1-5 Years	33,270
5-10 Years	1,530
5-10 Years	5,756
Fair Value	42,814	13,738
Government securities - Non-U.S.
Schedule of Available-for-sale Securities [Line Items]
Less than 1 Year	0
1-5 Years	0
5-10 Years	233
5-10 Years	0
Fair Value	233	1,063
Other fixed-income securities
Schedule of Available-for-sale Securities [Line Items]
Less than 1 Year	0
1-5 Years	8,199
5-10 Years	1,996
5-10 Years	276
Fair Value	10,471	3,992
Other securities
Schedule of Available-for-sale Securities [Line Items]
Less than 1 Year	81
1-5 Years	0
5-10 Years	0
5-10 Years	0
Fair Value	$ 81	$ 1,640