Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2018	Dec. 31, 2017
Preferred stock, shares authorized (in shares)	100,000,000	100,000,000
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	300,000,000	300,000,000
Common stock, shares issued (in shares)	64,563,291	72,563,291
Common stock held in treasury (in shares)	1,623,678	5,689,527
Series A Preferred Stock
Preferred stock, shares authorized (in shares)	10,896,250	10,896,250