Earnings per Share (Reconciliation of Number of Shares Used in Calculating Basic and Diluted Earnings per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Earnings per Share [Line Items]
Net income	$ 6,560	$ 14,597
Basic weighted-average shares outstanding	67,860	50,425
Diluted weighted-average shares outstanding	67,916	50,786
Basic net income per share	$ 0.10	$ 0.29
Diluted net income per share	$ 0.10	$ 0.29
Performance shares [Member]
Earnings per Share [Line Items]
Incremental shares	36	328
Restricted stock units [Member]
Earnings per Share [Line Items]
Incremental shares	20	33