Stockholders' Equity (Narrative) (Details) - USD ($)					1 Months Ended		3 Months Ended		9 Months Ended
	Sep. 02, 2016	Jun. 17, 2016	Apr. 15, 2016	Apr. 10, 2015	Feb. 29, 2016	Feb. 28, 2015	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average diluted shares outstanding excludes shares of common stock subject to stock options							171,514	237,384	219,302	284,884
Cash dividend (in usd per share)	$ 0.30	$ 0.30	$ 0.3	$ 2					$ 0.90
Payments of dividends	$ 7,400,000	$ 7,400,000	$ 7,300,000						$ 22,078,000	$ 48,227,000
Special dividend, stock per share or unit	0.30	0.30	0.30	$ 2.00
Dividend equivalents on stock-based awards	$ 300,000	$ 300,000	$ 300,000
Reduction in exercise price for all outstanding stock options				$ 2.00
Deferred stock units issued to executive officers					4,784	36,579
Deferred stock units issued to executive officers, aggregate fair value					$ 300,000	$ 2,000,000
Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Payments of dividends				$ 48,200,000
Deferred Stock Units, Restricted Stock and Stock Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividend equivalents on stock-based awards				$ 1,800,000
Weighted Average
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Deferred stock units issued to executive officers, exercise price					$ 55.22	$ 55.95