Summary of Significant Accounting Policies - Allowance for Doubtful Accounts Receivable (Details 2) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Allowance for Doubtful Accounts Receivable
Balance, beginning of year	$ 3,323	$ 2,359	$ 3,147
Additions (reductions) to expense	533	1,406	(354)
Write-offs	(318)	(465)	(280)
Recoveries	89
Other	(27)	23	(154)
Balance, end of year	$ 3,600	$ 3,323	$ 2,359