Stockholders' Equity and Earnings Per Share (Textual) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Nov. 08, 2013	Nov. 12, 2013
Class of Stock [Line Items]
Purchase of shares	$ 35,075,000	$ 31,306,000	$ 3,178,000
Options exercisable, contractual term	4 years
Options granted in period, shares	0
Options outstanding, shares	0
Stock option
Class of Stock [Line Items]
Options exercisable, expiration date	10 years
Shares Outstanding Class A
Class of Stock [Line Items]
Votes per share	1
Common stock, shares authorized	25,000,000
Treasury sock, shares	2,548,336	1,912,322
Common stock available for grant, shares	80,701
Shares Outstanding Class A | 2011 Stock Repurchase Program
Class of Stock [Line Items]
Stock repurchase program authorized amount				50,000,000
Purchase of shares	35,600,000
Shares Outstanding Class A | 2013 Stock Repurchase Program
Class of Stock [Line Items]
Stock repurchase program authorized amount					60,000,000
Purchase of shares	$ 35,100,000	$ 36,000,000
Treasury shares acquired	680,013
Shares Outstanding Class A | 2011 and 2013 Stock Repurchase Program
Class of Stock [Line Items]
Treasury shares acquired	663,918
Average cost per share (in dollars per share)	$ 52.83
Shares Outstanding Class B
Class of Stock [Line Items]
Votes per share	10
Common stock, shares authorized	6,756,176
Common stock available for grant, shares	80,100