Fair Value Measurements - Level 3 Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Business Combination, Contingent Consideration, Liability [Roll Forward]
Changes in fair value	$ 0	$ 3,680	$ 0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Business Combination, Contingent Consideration, Liability [Roll Forward]
Balance, Beginning of year	377	6,940
Cash payment	(167)	(2,883)
Changes in fair value	0	(3,680)
Balance, End of year	$ 210	$ 377	$ 6,940