Capital Stock (Details)	12 Months Ended
	Dec. 31, 2016 share_right $ / shares shares	Dec. 31, 2015 shares	Dec. 31, 2014 shares
Class of Warrant or Right [Line Items]
Common stock authorized (in shares)	150,000,000
Preferred stock authorized (in shares)	4,000,000
Preferred stock authorized, par value (in dollars per share) | $ / shares	$ 1.25
Shares Authorized to Be Purchased [Roll Forward]
Shares Authorized for Purchased, Beginning Balance	0	1,850,000	2,000,000
Shares Purchased		0	0
share repurchase - expired shares		1,253,368	0
Remaining Shares Authorized for Purchase, Ending Balance		0	1,850,000
Treasury Stock [Member]
Shares Authorized to Be Purchased [Roll Forward]
Shares Purchased	0	596,632	150,000
Preferred Stock Purchase Rights Agreement
Class of Warrant or Right [Line Items]
Number of rights distributed for each share of common stock outstanding | share_right	1
Minimum percentage of common stock to be acquired to trigger exercise of rights	15.00%
Number of securities called by rights (in shares)	0.01
Exercise price of warrant or right (in dollars per share) | $ / shares	$ 230.00
Multiplier of exercise price of right to determine common share purchase rights	2
Redemption price per right (in dollars per share) | $ / shares	$ 0.001
Number of business days following the acquisition of stock after which rights become exercisable	10 days
Preferred stock reserved for issuance upon exercise of rights (in shares)	801,750	800,944