Repurchases Of Common Stock (Details) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016 USD ($) $ / shares shares	Jun. 30, 2015 USD ($) $ / shares shares	Jun. 30, 2016 USD ($) $ / shares shares	Jun. 30, 2015 USD ($) $ / shares shares
Share repurchases	269,000	1,415,000	977,000	3,133,000
Shares acquired through employee surrender	2,000	2,000	54,000	64,000
Total shares repurchased	271,000	1,417,000	1,031,000	3,197,000
Cost of share repurchases | $	$ 23,260	$ 93,461	$ 72,975	$ 227,108
Cost of employee surrenders | $	203	195	3,732	5,061
Total cost of shares repurchased | $	$ 23,463	$ 93,656	$ 76,707	$ 232,169
Average cost per share | $ / shares	$ 86.46	$ 66.07	$ 74.38	$ 72.63
Stock split			2
Treasury Stock [Member]
Total shares repurchased		890,000		1,749,000