Condensed Consolidated Balance Sheets (Unaudited) (Paranthetical) - $ / shares	Jun. 30, 2019	Dec. 31, 2018
Statement Of Financial Position [Abstract]
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	25,000,000	25,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	500,000,000	500,000,000
Common stock, shares issued	144,764,125	144,383,662
Common stock, shares outstanding	137,690,627	137,438,353
Treasury stock, shares	7,073,498	6,945,309