Income Taxes - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities					$ 83,415
Provision for income taxes	$ 57,747	$ 46,068	$ 165,122	$ 156,427
Income from continuing operations before provision for income taxes	205,327	$ 200,832	$ 601,449	$ 619,862
U.S. federal statutory rate					21.00%	35.00%
Effective Income Tax Rate Reconciliation, Percent			27.50%	25.20%
Deferred income taxes	$ 296,199		$ 296,199		$ 311,434
Tax Cuts And Jobs Act of 2017 Transition Tax Adjustment for Accumulated Foreign Earnings Provisional Amount				$ 10,000
Excess Tax Benefit on Stock Based Payments			$ 1,000	$ 4,000
Effective Income Tax Rate Reconciliation, Change as a result of the Discrete Items, Percent			2.10%
Stahlgruber [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities					$ (78,130)