Revenue Recognition (Deferred Revenue) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Revenue Recognition [Abstract]
Balance at beginning of period	$ 67,681	$ 52,620	$ 59,915	$ 45,760
New contracts sold	11,119	8,054	32,504	25,226
Less: reductions for revenue recognized	(6,409)	(5,088)	(20,028)	(15,400)
Balance at end of period	$ 72,391	$ 55,586	$ 72,391	$ 55,586

Amount of deferred revenue recognized for transactions arising during the current reporting period. Deferred revenue is a liability as of the balance sheet date related to a revenue producing activity for which revenue has not yet been recognized. Generally, an Entity records deferred revenue when it receives consideration from a customer before achieving certain criteria that must be met for revenue to be recognized in conformity with GAAP.

No definition available.

Name:	us-gaap_DeferredRevenueAdditions
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration