Defined Contribution Plan (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Contribution Plan [Abstract]
401(k) matching contributions	$ 12,000,000.0	$ 11,000,000.0	$ 10,400,000
Matching contribution to 401(k) for every dollar	$ 0.75	$ 0.75	$ 0.75
Matching contribution percent to employee's contribution in pay period	7.00%	7.00%	7.00%