Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2018	Dec. 31, 2017
Common Stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common Stock, shares authorized (in shares)	200,000,000	200,000,000
Common Stock, shares issued (in shares)	67,901,000	68,236,000
Common Stock, shares outstanding (in shares)	67,901,000	68,236,000
Series D, G and I Preferred Stock
Liquidation preference (in dollars per share)	$ 25	$ 25
Preferred Stock Series J
Liquidation preference (in dollars per share)	$ 50.00	$ 50