Shareholders' Equity (Shareholders' Equity Narrative) (Details)	3 Months Ended						9 Months Ended
	Sep. 30, 2016 USD ($) vote $ / shares shares	Jun. 30, 2016 $ / shares	Mar. 31, 2016 $ / shares	Sep. 30, 2015 $ / shares	Jun. 30, 2015 $ / shares	Mar. 31, 2015 $ / shares	Sep. 30, 2016 USD ($) vote $ / shares shares	Sep. 30, 2015 USD ($) $ / shares	Dec. 31, 2015 vote $ / shares shares	Sep. 06, 2011 USD ($)
Share Repurchases [Line Items]
Preferred stock, authorized shares | shares	500,000.0						500,000.0		500,000.0
Preferred stock, par value (in dollars per share) | $ / shares	$ 0.01						$ 0.01		$ 0.01
Preferred stock, issued shares | shares	0						0		0
Total purchase price of common stock							$ 8,800,000	$ 0
Dividends declared per share (in dollars per share) | $ / shares	$ 0.30	$ 0.30	$ 0.30	$ 0.30	$ 0.30	$ 0.30	$ 0.90	$ 0.90
Common Class A [Member]
Share Repurchases [Line Items]
Number of votes | vote	1						1		1
Share repurchase program, authorized amount										$ 100,000,000
Number of shares repurchased | shares	0						984,190
Weighted average price per share (in dollars per share) | $ / shares							$ 8.96
Total purchase price of common stock							$ 8,800,000
Remaining authorized repurchases	$ 82,900,000						$ 82,900,000
Common Class B [Member]
Share Repurchases [Line Items]
Number of votes | vote	10						10		10
Common Class C [Member]
Share Repurchases [Line Items]
Number of votes | vote	10						10		10