Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2015	Dec. 31, 2014
Stockholders’ equity:
Preferred stock, par value (in usd per share)	$ 0.01	$ 0.01
Preferred stock, authorized (in shares)	60,000	60,000
Preferred stock, issued (in shares)	0	0
Common stock, par value (in usd per share)	$ 0.01	$ 0.01
Common stock, authorized (in shares)	150,000,000	150,000,000
Common stock, shares issues (in shares)	81,280,000	81,070,000
Treasury stock, shares (in shares)	7,351,000	8,157,000