Debt 4.25% Convertible Notes (Details) (USD $)	3 Months Ended					6 Months Ended
	Aug. 14, 2016	Jun. 30, 2012		Jun. 30, 2011		Jun. 30, 2012		Jun. 30, 2011		Dec. 31, 2011
Debt Instrument [Line Items]
Debt instrument, convertible, conversion price (in dollars per share)		$ 22.45		$ 22.45		$ 22.45		$ 22.45
Amortization of discount on the debt component						$ 4,710,000		$ 4,172,000
4.25% Convertible senior notes [Member]
Debt Instrument [Line Items]
Debt conversion, converted instrument, shares issued	44.5524
Principal amount of note to be considered under conversion rate	1,000
Debt instrument, convertible, conversion price (in dollars per share)		$ 22.45				$ 22.45
Debt instrument, interest rate, effective percentage		12.50%				12.50%
Principal amount of debt component		200,000,000	[1]			200,000,000	[1]			200,000,000	[1]
Convertible Debt, Principle Amount		200,000,000	[1]			200,000,000	[1]
Unamortized discount		(51,923,000)		(61,067,000)		(51,923,000)		(61,067,000)		(56,633,000)
Net carrying amount of debt component		148,077,000	[2]	138,933,000	[2]	148,077,000	[2]	138,933,000	[2]	143,367,000	[2]
Equity component		84,904,000		84,904,000		84,904,000		84,904,000		84,904,000
Issuance costs and income taxes related to convertible debt		(3,210,000)		(3,210,000)		(3,210,000)		(3,210,000)		(3,210,000)
Equity component, net of issuance costs and income taxes		81,694,000		81,694,000		81,694,000		81,694,000		81,694,000
4.25% coupon interest		2,125,000		2,125,000		4,250,000		4,250,000
Amortization of deferred financing fees		117,000		117,000		235,000		235,000
Amortization of discount on the debt component		2,390,000		2,117,000		4,710,000		4,172,000
Total interest expense related to the convertible notes		$ 4,632,000		$ 4,359,000		$ 9,195,000		$ 8,657,000

[1] As of June 30, 2012, December 31, 2011 and June 30, 2011, the Convertible Notes' "if-converted" value did not exceed their principal amount because the company's common stock price was below the conversion price of the Convertible Notes.

[2] The fair value of the parent company debt is based on observable inputs, which include quoted prices for similar assets or liabilities in an active market and market-corroborated inputs (Level 2). See also Note 7 for discussion of fair value.