Stockholders' Equity - Common Stock Issuance (Details) - USD ($) shares in Thousands, $ in Thousands									12 Months Ended
	Nov. 26, 2014		Apr. 07, 2014		Jan. 10, 2014		May. 03, 2013		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Stockholders' Equity Note [Abstract]
Shares Issued	14,410		14,950		11,500		13,600
Net Proceeds	$ 110,784	[1]	$ 109,916	[1]	$ 75,846	[1]	$ 94,434	[1]	$ 31,799	$ 296,546	$ 100,207

[1] Proceeds are net of underwriting costs and offering expenses paid by the Company.