Stockholders' Equity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016
Common Stock [Abstract]
Par value (in dollars per share)			$ 0.01	$ 0.01
Authorized shares (in shares)			85,000,000	85,000,000
Issued shares (in shares)			46,410,000	46,410,000
Outstanding shares (in shares)	40,738,000	40,738,000	40,738,000	40,738,000
Cumulative Preferred Stock [Abstract]
Par value (in dollars per share)			$ 0.01	$ 0.01
Authorized shares (in shares)			20,000,000	20,000,000
Issued shares (in shares)			0	0
Outstanding shares (in shares)			0	0
Changes in the outstanding shares of Common Stock [Roll Forward]
Common stock outstanding at beginning of period (in shares)	40,738,000	40,738,000
Common stock repurchased for treasury (in shares)	0	0
Issuance of treasury stock (in shares)	0	0
Common stock outstanding at end of period (in shares)	40,738,000	40,738,000
Changes in the treasury shares of Common Stock [Abstract]
Treasury stock held at beginning of period (in shares)	5,672,000	5,672,000
Common stock repurchased for treasury (in shares)	0	0
Issuance of treasury stock (in shares)	0	0
Treasury stock held at end of period (in shares)	5,672,000	5,672,000
Common Stock Repurchase Plan [Abstract]
Common shares repurchased to treasury during the period (in shares)	0	0
Aggregate cost of shares repurchased during the period	$ 0
Total number of common shares authorized for repurchase (in shares)			10,000,000
Total number of common shares repurchased to date (in shares)			6,226,000
Total number of shares that may yet be repurchased (in shares)			3,774,000
Common stock reserved for issuance under Company's stock option and other employee benefit plans [Abstract]
1993 Stock Incentive Plan (in shares)			4,320,000
Total Common shares reserved for issuance (in shares)			4,320,000
Stockholder Rights Plan [Abstract]
Dividends declared, number of right per common share (in shares)			1
Exercise price of rights (in dollars per share)			$ 75.00
Minimum percentage of outstanding common shares to be acquired			25.00%
Minimum percentage of outstanding common shares for tender offer			20.00%
Redemption price of rights (in dollars per share)			$ 0.05
Minimum percentage of common shares by a single acquirer or group			20.00%
Period after accumulation of minimum percentage of common shares to invoke redemption of rights	10 days