Commitments and Contingencies (Narrative) (Details)		1 Months Ended	3 Months Ended
	Dec. 11, 2009 plaintiff claim	Nov. 30, 2015 claim	Mar. 31, 2018
Commitments And Contingencies Disclosure [Abstract]
Participant's retirement age			65 years
Number of plaintiffs | plaintiff	2
New claims	2	3
Claims Dismissed		2