Revenue Recognition (Deferred Revenue) (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenue Recognition [Abstract]
Balance at beginning of period			$ 45,760,000	$ 26,157,000
New contracts sold	$ 8,054,000	$ 6,962,000	25,226,000	22,076,000
Less: reductions for revenue recognized	(5,088,000)	(3,130,000)	(15,400,000)	(8,213,000)
Balance at end of period	$ 55,586,000	$ 40,020,000	$ 55,586,000	$ 40,020,000