Stockholders' Equity (Narrative) (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended		6 Months Ended
	Dec. 31, 2017	Nov. 30, 2017	Dec. 31, 2017	Dec. 31, 2016	Jun. 30, 2017	Apr. 30, 1997
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common shares repurchased under repurchase program			100,000
Cost of common shares repurchased			$ 8,500
Total number of shares repurchased pursuant to the repurchase program	41,186,234		41,186,234		41,086,234
Total cost of shares repurchased pursuant to the repurchase program	$ 1,555,152		$ 1,555,152		$ 1,546,611
Additional shares that can be repurchased under the approved share repurchase program	13,500,000		13,500,000
Preferred stock, shares authorized	2,000,000		2,000,000		2,000,000
Preferred stock at par value	$ 0.01		$ 0.01		$ 0.01
Preferred stock, shares issued	0		0		0
Series A Junior Participating Preferred Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Preferred stock, shares authorized						2,000,000
Preferred stock at par value						$ 0.01
Preferred stock, shares issued	0		0		0
Preferred stock, shares outstanding	0		0		0
2009 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration period			7 years
Maximum amount payable pursant to cash denominated performance awards granted	$ 5,000	$ 3,000
Vesting period		4 years
Expiration date		Sep. 11, 2027
Common stock authorized for issuance	51,100,000		51,100,000
Common stock authorized for issuance and pending registration		7,400,000
Number of securities remaining available for future issuance	17,600,000		17,600,000
2009 Plan [Member] | Non Employee Director [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum award amount with other cash fees earned for services		$ 700
2009 Plan [Member] | Board Of Directors Chairman [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum award amount with other cash fees earned for services		$ 1,200
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of securities remaining available for future issuance	700,000		700,000
Shares issued under Employee Stock Purchase Plan			148,000	142,000
Minimum [Member] | 2009 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period			1 year
Maximum [Member] | 2009 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period			4 years