Organization and Summary of Significant Accounting Policies - Defined Benefit Assumption and Advertising Costs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Expected long term rate of return for defined benefit plans
Time period for average rate of return	20 years
Percentage of greater of projected benefit obligation or fair value of plan assets for amortization of actuarial gains or losses	5.00%
Amortization period for actuarial gains and losses that exceed threshold	5 years
Advertising
Advertising costs	$ 6.2	$ 6.1	$ 5.5