Employee Benefit Plans (Narrative) (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Retirement Benefits [Abstract]
Defined benefit plan, employer contributions			$ 2,500,000	$ 2,000,000
Defined benefit plans, estimated future employer contributions	$ 0		0
Defined contribution plan, compensation expense	$ 900,000	$ 900,000	$ 3,000,000	$ 2,600,000