Operating Leases - (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Jan. 01, 2019
Leases [Line Items]
Operating lease, right-of-use asset	$ 113,447	$ 115,900
Operating lease payment obligation	$ 128,494	130,700
Decrease in existing lease incentive and other deferred rent liabilities		$ 14,800
Lessee, operating lease, existence of option to extend [true/false]	false
Lessee, operating lease, option to extend	As these extension options are not generally considered reasonably certain of renewal, they are not included in the lease term.
Minimum [Member]
Leases [Line Items]
Lessee, operating lease, term of contract	5 years
Lessee, operating lease, renewal term	1 year
Maximum [Member]
Leases [Line Items]
Lessee, operating lease, term of contract	20 years
Lessee, operating lease, renewal term	20 years