Shareholders' Equity (Details) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2016 USD ($) $ / shares shares
Class of Warrant or Right [Line Items]
Common stock, beneficial ownership threshold to be considered an Acquiring Person (in hundredths)	5.00%
Shareholder rights accompanying each outstanding share of the company's common stock (in number of Rights) | shares	1
Purchase price (in dollars per share) | $ / shares	$ 45
Purchase price (in dollars per one-tenth share) | $ / shares	4.50
Redemption price (in dollars per Right) | $ / shares	$ 0.001
Common shares purchasable per Right (in shares) | shares	0.1
Rights
Class of Warrant or Right [Line Items]
Number of rights per outstanding share of common stock | shares	1
Period after public announcement that a person has become an acquirer	10 days
Period after a person announces a tender offer which would make them an acquirer	10 days
Convertible Junior Debentures at 9% per annum, Due 2063
Class of Warrant or Right [Line Items]
Reacquisition of convertible junior subordinated debentures-equity component | $	$ 9.8
Stated interest rate	9.00%