Earnings per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
Mar. 31, 2017	Mar. 31, 2016
Earnings per Share
Adjustments to net income (in dollars)	$ 0	$ 0
Antidilutive securities (in shares)	0	0
Numerator:
Net income	$ 56,740	$ 65,531
Denominator:
Basic: weighted-average shares outstanding (in shares)	139,545,728	139,459,620
Add: weighted-average equity-based awards (in shares)	91,682
Diluted: weighted-average shares outstanding (in shares)	139,637,410	139,459,620
Basic earnings per share (in dollars per share)	$ 0.41	$ 0.47
Diluted earnings per share (in dollars per share)	$ 0.41	$ 0.47

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.

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The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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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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Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of share based payment arrangements using the treasury stock method.

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Net income after adjustments for dividends on preferred stock (declared in the period) and/or cumulative preferred stock (accumulated for the period).

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