Consolidated Statements Of Stockholders' Equity (Parenthetical) - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
TREASURY STOCK, AT COST:
Purchases, shares	0	1,380	3,850
RETAINED EARNINGS:
Cash dividends declared on common stock, per share	$ 2.19	$ 1.56	$ 2.32