CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (Parenthetical) (USD $)	3 Months Ended												12 Months Ended			77 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2014
Statement of Stockholders' Equity [Abstract]
Treasury stock purchased, shares													15,650	12,200	23,640	122,490
Treasury stock issued, shares													16,460	16,274	16,761
Cash dividends paid, per share	$ 0.27	$ 0.27	$ 0.27	$ 0.26	$ 0.26	$ 0.26	$ 0.26	$ 0.26	$ 0.25	$ 0.25	$ 0.25	$ 0.25	$ 1.07	$ 1.04	$ 1.00