New Accounting Pronouncements (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' equity	$ 3,918,002	$ 3,795,178	$ 4,053,831	$ 3,776,259	$ 3,725,057	$ 3,605,453
Allowances on accounts receivable, current	14,948		9,398
Deferred income taxes	(220,689)		(214,779)
Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' equity	$ 2,948,180	$ 2,881,416	2,854,271	$ 2,612,994	$ 2,591,883	$ 2,477,291
Adjustment due to Adoption of New ASU
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' equity			(3,841)
Allowances on accounts receivable, current			5,100
Deferred income taxes			1,200
Adjustment due to Adoption of New ASU | Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' equity			$ (3,841)