Stockholders' Equity Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Equity [Abstract]
Weighted average common shares outstanding – basic		61,112,051	59,832,824	60,457,949	56,026,594
Effect of dilutive shares underlying stock-based compensation		144,000	30,000	109,000	13,000
Incremental common shares attributable to shares issued from pre-spin dividend				0	3,429,000
Weighted average common shares outstanding – diluted	[1]	61,256,145	59,863,109	60,567,152	59,469,008
Net income available to common shareholders		$ 19,205	$ 15,240	$ 53,044	$ 124,325
Basic net income per share (in USD per share)		$ 0.31	$ 0.25	$ 0.88	$ 2.22
Diluted net income per share (in USD per share)		$ 0.31	$ 0.25	$ 0.88	$ 2.09
Antidilutive securities excluded from computation of earnings per share, amount		271,443	221,183	270,749	209,566
Weighted average units of partnership interest, amount		409,320		425,729

[1] Includes 17,085,566 shares issued on March 2, 2016 as part of our purging distribution to satisfy certain REIT requirements. For financial reporting purposes, these shares were assumed to have been issued on January 7, 2016.