Consolidated Statements of Changes In Shareholders' Equity (Parenthetical) - $ / shares	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Statement of Stockholders' Equity [Abstract]
Cash dividends (in dollars per share)	$ 0.60	$ 0.60
Class A Common Stock
Statement of Stockholders' Equity [Abstract]
Repurchase of common stock (in shares)	0	0
Class B Common Stock
Statement of Stockholders' Equity [Abstract]
Repurchase of common stock (in shares)	0	0