Summary of Significant Accounting Policies (Allowance for Doubtful Accounts) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Changes in the allowance for doubtful accounts
Balance, beginning of year	$ 847	$ 872	$ 714
Charged to provision for doubtful accounts	1,132	481	570
Write-offs	(790)	(506)	(412)
Balance, end of year	$ 1,189	$ 847	$ 872