Fair Value Measurements - Contractual Maturities of Available for Sale Investments (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Total debt securities	$ 69,496
Municipal Bonds — Available for Sale
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Maturing in one year or less	774	$ 4,343
Maturing after one year through five years	13,852	7,456
Maturing after five years through ten years	36,273	0
Maturing after ten years	18,597	0
Total debt securities	$ 69,496	$ 11,799