Debt Unsecured Loan and Note Payable (Details) (USD $)	3 Months Ended	9 Months Ended	12 Months Ended			0 Months Ended
	Dec. 31, 2013	Oct. 06, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Aug. 15, 2014
Debt Instrument [Line Items]
Proceeds from mortgage notes payable	$ 0		$ 191,000,000
Senior unsecured notes	0		237,667,000	0
Interest expense	(13,147,000)	(50,660,000)	(66,456,000)		(54,394,000)
Amortization of deferred finance costs and debt premiums and discount			7,600,000	12,700,000	4,900,000
Convertible Debt [Member] | Exchangeable Senior Notes due August 15, 2019 [Member]
Debt Instrument [Line Items]
Face amount						250,000,000
Debt Instrument, Interest Rate, Stated Percentage						2.625%
Proceeds from mortgage notes payable						246,900,000
Shares converted						51.4059
Conversion price						$ 19.45
Percentage of principal redeemed						100.00%
Effective Rate						3.80%
Senior unsecured notes						236,600,000
Embedded conversion option			13,400,000
Remaining discount amortization period						5 years
Unamortized discount			12,300,000
Underwriting expense						3,100,000
Deferred finance costs						2,900,000
Embedded conversion feature, reduction			200,000
Interest on note			3,800,000
Interest expense			(2,500,000)
Accretion of debt discount			1,100,000
Amortization of deferred finance costs and debt premiums and discount			$ 200,000
Covenant Scenario One [Member] | Convertible Debt [Member] | Exchangeable Senior Notes due August 15, 2019 [Member]
Debt Instrument [Line Items]
Threshold Percentage of Stock Price Trigger						130.00%
Threshold trading days						20
Threshold consecutive trading days						30 days
Covenant Scenario Two [Member] | Convertible Debt [Member] | Exchangeable Senior Notes due August 15, 2019 [Member]
Debt Instrument [Line Items]
Threshold Percentage of Stock Price Trigger						98.00%
Threshold consecutive trading days						5 years
Threshold consecutive business days						5 years