Capital Stock (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2015	Dec. 31, 2014
Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Common stock, shares authorized				100,000,000	100,000,000
Common stock, par value (in dollars per share)				$ 0.01	$ 0.01
Preferred stock, shares authorized				5,000,000
Preferred stock, par value				$ 0.01
Common Stock, Shares, Outstanding	79,649,946	78,855,547	78,112,032	80,256,670	79,649,946
Treasury stock, shares held	2,672,930	2,478,084	2,334,137	2,766,958	2,672,930
Preferred stock, shares issued				0
Common Shares Outstanding and Treasury Shares Held Rollforward [Table]
Common shares outstanding, beginning balance	79,649,946	78,855,547	78,112,032
Exercise of common stock options, net	67,808	290,369	373,106
Grants of restricted stock, net	538,916	504,030	370,409
Common shares outstanding, ending balance	80,256,670	79,649,946	78,855,547
Treasury stock, beginning balance	2,672,930	2,478,084	2,334,137
Shares received upon exercise of common stock options	36,818	189,469	119,477
Shares received upon vesting of restricted stock, net	57,210	5,377	24,470
Treasury stock, ending balance	2,766,958	2,672,930	2,478,084
Amount authorized under stock repurchase program				$ 20,000,000
Amount repurchased under the stock repurchase program in the period	$ 0