Earnings per Share ("EPS") (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Basic EPS
Net Income (Numerator)	$ 153,151	$ 126,351	$ 93,473
Shares (Denominator)	66,872,500	67,195,180	67,236,681
Per Share Amount	$ 2.29us-gaap_EarningsPerShareBasic	$ 1.88us-gaap_EarningsPerShareBasic	$ 1.39us-gaap_EarningsPerShareBasic
Diluted EPS
Net Income (Numerator)	$ 153,151	$ 126,351	$ 93,473
Potential dilutive common shares and warrants	183,956	119,679	77,282
Shares (Denominator)	67,056,456	67,314,859	67,313,963
Per Share Amount (in dollars per share)	$ 2.28us-gaap_EarningsPerShareDiluted	$ 1.88us-gaap_EarningsPerShareDiluted	$ 1.39us-gaap_EarningsPerShareDiluted

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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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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