Retirement Plans (Narrative) (Details) - Pension Plan $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($) plan
Defined Benefit Plan Disclosure
Defined contribution plan number	6
United States
Defined Benefit Plan Disclosure
Number of retirement plans	3
Defined Benefit Plan Number	1
Defined contribution plan number	2
Defined benefit plans, estimated future employer contributions in current fiscal year | $	$ 550
Canada
Defined Benefit Plan Disclosure
Defined contribution plan number	2
United Kingdom
Defined Benefit Plan Disclosure
Defined contribution plan number	2
Defined benefit plans, estimated future employer contributions in current fiscal year | $	$ 255
Defined benefit plan, contributions by employer | $	$ 64