Earnings Per Share ("EPS") (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Earnings Per Share [Abstract]
Net income	$ 47,695	$ 51,312
Average common shares outstanding (in shares)	92,520	92,182
Average potential dilutive common shares (in shares)	351	457
Average diluted common shares (in shares)	92,871	92,639
Basic earnings per share (in dollars per share)	$ 0.52	$ 0.56
Diluted earnings per share (in dollars per share)	$ 0.51	$ 0.55