Income Taxes Schedule of Effective Income Tax Rate Reconciliation (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Income Tax Disclosure [Abstract]
Income before income tax expense	$ 131,866	$ 48,450	$ 318,620	$ 201,493
Income tax expense	$ 30,401	$ 18,806	$ 78,410	$ 69,358
Effective tax rate	23.10%	38.80%	24.60%	34.40%