Accounting Standards Adopted and Newly Issued Accounting Standards Not Yet Adopted - Narrative (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
	Jan. 01, 2019	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease obligations		$ 437,000		$ 437,000
Operating lease right-of-use assets		370,500		370,500		$ 0
Adoption of ASC 842	$ 5,030
Income tax provision		$ 7,815	$ 7,660	$ 24,981	$ 25,181
Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Adoption of ASC 842	5,030
Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease obligations	453,000
Operating lease right-of-use assets	395,600
Income tax provision	(1,700)
Derecognition of certain liabilities and assets	(50,700)
Accrued rent	(43,300)
Accounting Standards Update 2016-02 | Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Adoption of ASC 842	$ 5,000