Consolidated Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 2016	Dec. 31, 2015
Statement Of Financial Position [Abstract]
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	20,000,000	20,000,000
Preferred stock, liquidation preference	$ 50	$ 50
Preferred stock, shares issued	868,000	868,000
Preferred stock, shares outstanding	868,000	868,000
Common stock, par value	$ 0.01	$ 0.01
Common stock, authorized	100,000,000	100,000,000
Common stock, shares issued	54,632,000	54,632,000
Common stock, shares outstanding	53,490,000	54,012,000
Common stock in treasury, shares	1,225,000	706,000