Stockholders' Equity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Class of Stock [Line Items]
Preferred Stock, Liquidation Preference Per Share	$ 0.60
Preferred Stock, Dividend Rate, Percentage	0.03
Preferred Stock, Redemption Price Per Share	$ 0.60
Common stock, shares outstanding	24,893,955	24,808,176	24,715,316	24,754,355
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures	96,101	159,764	390,707
Issuance of common stock under compensation plans	$ 3,718	$ 5,022	$ 12,028
Shares of common stock repurchased	(10,322)	(66,904)	(429,746)
Purchase of common stock	$ (586)	$ (3,742)	$ (18,460)
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 49,500
Common Class A
Class of Stock [Line Items]
Common stock, shares outstanding	24,882,542	24,796,763	24,703,903	24,742,942
Common stock, without par value	$ 152,903	$ 149,248
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures	96,101	159,764	390,707
Shares of common stock repurchased	(10,322)	(66,904)	(429,746)
Board of directors members	four to ten
Purchase of shares of common stock	$ 600	$ 3,700	$ 18,500
Common Class B
Class of Stock [Line Items]
Common stock, shares outstanding	11,413	11,413	11,413	11,413
Common stock, without par value	$ 72	$ 72
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures	0	0	0
Shares of common stock repurchased	0	0	0
Board of directors members	five to seven
Parent Company [Member]
Class of Stock [Line Items]
Sale of Stock, Percentage of Ownership after Transaction	71.00%
Common stocks
Class of Stock [Line Items]
Common stock, without par value	$ 152,975	$ 149,320	$ 144,697	$ 135,065
Issuance of common stock under compensation plans	3,718	5,022	12,028
Purchase of common stock	(63)	(399)	(2,396)
Common stocks | Common Class A
Class of Stock [Line Items]
Common stock, without par value	152,903	149,248	144,625	134,993
Issuance of common stock under compensation plans	3,718	5,022	12,028
Purchase of common stock	(63)	(399)	(2,396)
Common stocks | Common Class B
Class of Stock [Line Items]
Common stock, without par value	72	72	72	$ 72
Issuance of common stock under compensation plans	0	0	0
Purchase of common stock	$ 0	$ 0	$ 0