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v3.4.0.3

Shareholders' equity (Details) - USD ($) | 3 Months Ended | 12 Months Ended | 60 Months Ended |  |
--- | --- | --- | --- | --- | ---
Mar. 31, 2016 | Mar. 31, 2015 | Mar. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2011 | Dec. 31, 2008
Class of Stock [Line Items] |  |  |  |  |  |
Common stock, shares authorized (in shares) | 195,000,000 |  | 195,000,000 | 195,000,000 |  |
Common stock, par value (in dollars per share) | $ 0.01 |  | $ 0.01 | $ 0.001 |  |
Common stock, shares issued | 94,246,254 |  | 94,246,254 | 94,224,571 |  |
Common stock, shares outstanding | 87,059,733 |  | 87,059,733 | 87,038,050 |  |
Stock repurchase program, authorized amount |  |  |  | $ 130,000,000 | $ 60,000,000 |
Repurchase of common stock (in shares) |  |  | 0 | 7,186,521 |  |
Repurchase of common stock, aggregate purchase price |  |  |  | $ 86,276,000 |  |
Stock repurchase program, remaining authorized repurchase amount | $ 43,724,000 |  | $ 43,724,000 |  |  |
Preferred stock, shares authorized | 5,000,000 |  | 5,000,000 | 5,000,000 |  |
Preferred stock par value (in dollars per share) | $ 0.01 |  | $ 0.01 | $ 0.001 |  |
Preferred shares issued |  |  |  |  |  | 160,000
Number of shares issued for each share of preferred stock | 100 |  | 100 |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |  |
Repurchase of common stock (in shares) |  |  | 0 | 7,186,521 |  |
Series A Convertible Preferred Stock [Member] |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |
Repurchase of common stock (in shares) | 0 | 0 |  |  |  |
Preferred stock par value (in dollars per share) | $ 0.01 |  | $ 0.01 |  |  |
Preferred shares outstanding | 76,446 |  | 76,446 | 76,539 |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |  |
Shares, Beginning balance (in shares) | 76,539 | 78,141 | 78,061 |  |  |
Repurchase of common stock (in shares) | 0 | 0 |  |  |  |
Conversion of convertible preferred stock (in shares) | (93) | (80) |  |  |  |
Issuance for stock compensation plans (in shares) | 0 | 0 |  |  |  |
Shares, Ending balance (in shares) | 76,446 | 78,061 | 76,446 | 76,539 |  |
Treasury Stock [Member] |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |
Repurchase of common stock (in shares) | 0 | 1,200,000 |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |  |
Shares, Beginning balance (in shares) | 7,186,521 | 4,786,521 | 5,986,521 |  |  |
Repurchase of common stock (in shares) | 0 | 1,200,000 |  |  |  |
Conversion of convertible preferred stock (in shares) | 0 | 0 |  |  |  |
Issuance for stock compensation plans (in shares) | 0 | 0 |  |  |  |
Shares, Ending balance (in shares) | 7,186,521 | 5,986,521 | 7,186,521 | 7,186,521 |  |
Common Stock [Member] |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |
Repurchase of common stock (in shares) | 0 | (1,200,000) |  |  |  |
Increase (Decrease) in Stockholders' Equity [Roll Forward] |  |  |  |  |  |
Shares, Beginning balance (in shares) | 87,038,050 | 89,064,582 | 87,883,357 |  |  |
Repurchase of common stock (in shares) | 0 | (1,200,000) |  |  |  |
Conversion of convertible preferred stock (in shares) | 9,305 | 7,947 |  |  |  |
Issuance for stock compensation plans (in shares) | 12,378 | 10,828 |  |  |  |
Shares, Ending balance (in shares) | 87,059,733 | 87,883,357 | 87,059,733 | 87,038,050 |  |

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