Common Stock Repurchase Plan (Details) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($) shares
Common Stock Repurchase Plan [Abstract]
Common shares repurchased to treasury during the period (in shares)	0
Aggregate cost of shares repurchased during period | $	$ 0
Total number of common shares authorized for repurchase (in shares)	10,000
Total number of common shares repurchased to date (in shares)	6,226
Total number of shares that may yet be repurchased (in shares)	3,774