Leases (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2018	Sep. 30, 2019	Jan. 01, 2019
Lessee, Lease, Description [Line Items]
Operating lease right-of-use assets			$ 45,834
Operating lease liabilities			$ 48,699
Weighted-average remaining lease term (in years):			4 years 4 months 24 days
Lessee, operating lease, not yet commenced, amount			$ 2,000
Rent expense	$ 3,800	$ 11,400
Accounting Standards Update 2016-02 [Member]
Lessee, Lease, Description [Line Items]
Operating lease right-of-use assets				$ 41,000
Operating lease liabilities				43,000
Deferred rent credit				$ 2,000
Minimum [Member]
Lessee, Lease, Description [Line Items]
Weighted-average remaining lease term (in years):			1 year
Lessee, operating lease, lease not yet commenced, term of contract			1 year
Maximum [Member]
Lessee, Lease, Description [Line Items]
Weighted-average remaining lease term (in years):			8 years
Lessee, operating lease, lease not yet commenced, term of contract			3 years