Common Stock (Reconciliation of Common Shares Issued and Additional Disclosures) (Details)		12 Months Ended
	Nov. 09, 2009 series $ / shares shares	Dec. 31, 2018 $ / shares shares	Dec. 31, 2017 $ / shares shares
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Common stock, shares authorized (in shares)	80,000,000	80,000,000	80,000,000
Common stock, par value (in dollars per share) | $ / shares	$ 0.0001	$ 0.0001	$ 0.0001
Preferred stock. shares authorized (in shares)	100,000	100,000	100,000
Preferred stock, minimum number of series authorized | series	1
Preferred stock, par value (in dollars per share) | $ / shares	$ 0.0001	$ 0.0001	$ 0.0001
Increase (Decrease) in Stockholders' Equity
Shares issued at the beginning of the year (in shares)		60,622,986	59,684,669
Issued as restricted stock award grants (in shares)		1,539,889	275,029
Issued upon exercise of stock options (in shares)		0	663,288
Shares issued at the end of the year (in shares)		62,162,875	60,622,986