Net Earnings Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
Mar. 31, 2015 item	Mar. 31, 2014
Net Earnings Per Share
Number of classes of common stock	2al_NumberOfClassesOfCommonStock
Numerator
Net income	$ 19,332	$ 61,397
Denominator
Number of shares used in basic computation	102,455,040	101,857,176
Basic net income per share (in dollars per share)	$ 0.19us-gaap_EarningsPerShareBasic	$ 0.60us-gaap_EarningsPerShareBasic
Numerator
Net income	19,332	61,397
Assumed conversion of convertible senior notes	1,433	1,433
Net income plus assumed conversions	$ 20,765	$ 62,830
Denominator
Number of shares used in basic computation	102,455,040	101,857,176
Weighted-average effect of dilutive securities (in shares)	8,103,669	8,180,206
Number of shares used in per share computation	110,558,709	110,037,382
Diluted net income per share (in dollars per share)	$ 0.19us-gaap_EarningsPerShareDiluted	$ 0.57us-gaap_EarningsPerShareDiluted
Restricted Stock Units
Anti-dilutive securities
Anti-dilutive securities excluded from the computation of diluted earnings per share (in shares)	936,968	1,789,586

Represents the number of classes of common stock.

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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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The after-tax amount of interest recognized in the period associated with any convertible debt.

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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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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 sum of dilutive potential common shares or units used in the calculation of the diluted per-share or per-unit computation.

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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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