Stockholders' Equity (Narrative) (Details) - USD ($)			1 Months Ended	3 Months Ended		9 Months Ended
	Apr. 10, 2015	Jan. 06, 2014	Feb. 28, 2015	Sep. 30, 2015	Mar. 31, 2014	Sep. 30, 2015	Sep. 30, 2014
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				237,384	322,542	284,884	322,542
Special cash dividend (in usd per share)	$ 2.00	$ 2.00				$ 2
Special dividend, stock per share or unit	$ 2.00	$ 2.00
Reduction in exercise price for all outstanding stock options	$ 2.00	$ 2.00
Deferred stock units issued to executive officers			36,579	43,188
Deferred stock units issued to executive officers, exercise price				$ 45.98
Deferred stock units issued to executive officers, aggregate fair value			$ 2,000,000	$ 2,000,000
Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Payments of special dividends	$ 48,200,000	$ 46,700,000
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	$ 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			$ 55.95