Leases (Narrative) (Details) $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2019 USD ($)	Sep. 30, 2019 USD ($) item	Dec. 31, 2018 USD ($)	Mar. 08, 2019 USD ($)	Jan. 01, 2019 USD ($)
Operating Leased Assets [Line Items]
Net present value of operating lease aggrements	$ 23,316	$ 23,316
Weighted average discount rate	5.40%	5.40%			5.50%
Weighted average remaining lease term	5 years 8 months 12 days	5 years 8 months 12 days			6 years
Deferred rent obligations	$ 2,400	$ 2,400
Operating lease, option to terminate, period		29 years
Operating lease, termination option, notice period requirement		2 years
Right-of-use asset	21,841	$ 21,841
Number of subleases | item		2
Sublease income	$ 227	$ 679	$ 910
Minimum [Member]
Operating Leased Assets [Line Items]
Lease terms	1 year	1 year
Maximum [Member]
Operating Leased Assets [Line Items]
Lease terms	11 years	11 years
Lease period of omitted leases		12 months
On-X [Member]
Operating Leased Assets [Line Items]
Right-of-use asset				$ 3,700
Discount rate				5.83%
Accounting Standards Update 2016-02 [Member]
Operating Leased Assets [Line Items]
Net present value of operating lease aggrements					$ 22,700