Earnings Per Share - Diluted (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Diluted earnings per share
Net income available for common stockholders, net of dividends and undistributed earnings allocated to participating securities	$ 571	$ 8,178	$ 4,798	$ 18,305
Weighted average shares of common stock outstanding
Issued and outstanding	40,814,214	38,230,684	40,607,791	38,220,390
Weighted average number of shares of common stock outstanding	40,814,214	38,230,684	40,607,791	38,220,390
Diluted Earnings per share	$ 0.01	$ 0.21	$ 0.11	$ 0.48
Anti-dilutive shares excluded from computation of EPS	1,047,193	476,249	912,157	73,259
Class A
Weighted average shares of common stock outstanding
Issued and outstanding	40,814,214	38,230,684	40,607,791	38,220,390

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Antidilution
-URI http://asc.fasb.org/extlink&oid=6505113

Reference 2: http://www.xbrl.org/2003/role/presentationRef
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-URI http://asc.fasb.org/extlink&oid=6510752

Reference 3: http://www.xbrl.org/2003/role/presentationRef
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The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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Net Income or Loss Available to Common Stockholders plus adjustments resulting from the assumption that dilutive convertible securities were converted, options or warrants were exercised, or that other shares were issued upon the satisfaction of certain conditions.

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The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period.

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Number of [basic] shares or units, after adjustment for contingently issuable shares or units and other shares or units not deemed outstanding, determined by relating the portion of time within a reporting period that common shares or units have been outstanding to the total time in that period.

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