New Accounting Principles and Recent Accounting Pronouncements 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	[1]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease assets	$ 618,100	$ 565,987		$ 565,987		$ 0
Current operating lease liabilities	155,500	117,071		117,071		$ 0
Non-current lease liabilities	468,400
Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative-effect adjustment to retained earnings	$ 116,800	$ 0	$ 0	$ 116,768	$ 0

[1] Reclassified to conform to current presentation (see Note A).