Related-Party Transactions (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Related Party Transaction [Line Items]
Deferred compensation	$ 26,543		$ 26,543		$ 25,493
Fair value of common stock	738		738		805
Deferred compensation expense	860	$ 417	1,100	$ 996
Synthonics
Related Party Transaction [Line Items]
Cost method investments	$ 2,170		$ 2,170		$ 2,170
Cost method, ownership percentage	18.30%		18.30%		18.30%