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Earnings Per Share - Reconciliation of Numerators and Denominators of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands | 3 Months Ended | 12 Months Ended
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Dec. 31, 2017 | Sep. 30, 2017 | Jun. 30, 2017 | Mar. 31, 2017 | Dec. 31, 2016 | Sep. 30, 2016 | Jun. 30, 2016 | Mar. 31, 2016 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Numerator for Earnings per Common Share-Basic: |  |  |  |  |  |  |  |  |  |  |
Net Income |  |  |  |  |  |  |  |  | $ 72,968 | $ 71,392 | $ 67,081
Less: Income allocated to participating shares |  |  |  |  |  |  |  |  | 242 | 225 | 280
Net Income Allocated to Common Shareholders | $ 9,294 | $ 22,721 | $ 22,765 | $ 18,188 | $ 17,659 | $ 20,581 | $ 17,059 | $ 16,093 | 72,726 | 71,167 | 66,801
Numerator for Earnings per Common Share—Diluted: |  |  |  |  |  |  |  |  |  |  |
Net Income |  |  |  |  |  |  |  |  | $ 72,968 | $ 71,392 | $ 67,081
Denominators: |  |  |  |  |  |  |  |  |  |  |
Weighted Average Common Shares Outstanding-Basic (in shares) |  |  |  |  |  |  |  |  | 34,729,376 | 34,677,738 | 33,812,990
Add: Dilutive potential common shares (in shares) |  |  |  |  |  |  |  |  | 225,391 | 95,432 | 35,092
Denominator for Treasury Stock Method-Diluted (in shares) |  |  |  |  |  |  |  |  | 34,954,767 | 34,773,170 | 33,848,082
Weighted Average Common Shares Outstanding-Basic (in shares) |  |  |  |  |  |  |  |  | 34,729,376 | 34,677,738 | 33,812,990
Add: Average participating shares outstanding (in shares) |  |  |  |  |  |  |  |  | 115,418 | 109,755 | 141,558
Denominator for Two-Class Method-Diluted (in shares) |  |  |  |  |  |  |  |  | 34,844,794 | 34,787,493 | 33,954,548
Earnings per common share—basic (in USD per share) |  |  |  |  |  |  |  |  | $ 2.10 | $ 2.06 | $ 1.98
Earnings per common share—diluted (in USD per share) | $ 0.27 | $ 0.65 | $ 0.65 | $ 0.52 | $ 0.51 | $ 0.59 | $ 0.49 | $ 0.46 | 2.09 | 2.05 | 1.98
Exercise price of warrants (in USD per share) | $ 31.53 |  |  |  | $ 31.53 |  |  |  | $ 31.53 | $ 31.53 | $ 31.53
Warrants |  |  |  |  |  |  |  |  |  |  |
Denominators: |  |  |  |  |  |  |  |  |  |  |
Anti-dilutive excluded from dilutive potential common shares (in shares) |  |  |  |  |  |  |  |  | 438,681 | 517,012 | 517,012
Restricted Stock |  |  |  |  |  |  |  |  |  |  |
Denominators: |  |  |  |  |  |  |  |  |  |  |
Anti-dilutive excluded from dilutive potential common shares (in shares) |  |  |  |  |  |  |  |  | 88,578 | 116,749 | 106,466

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- Definition The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 55 -Paragraph 52 -URI http://asc.fasb.org/extlink&oid=96948231&loc=d3e4984-109258 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04(19)) -URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=96947427&loc=d3e1252-109256 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03(21)) -URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04(23)) -URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882 + Details
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- Definition This element represents nonvested share-based payment awards that contain non-forfeitable rights to dividends or dividend equivalents (whether paid or unpaid). Basic and dilutive earnings per share are generally disclosed for such shares using the two-class method. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 45 -Paragraph 61A -URI http://asc.fasb.org/extlink&oid=96947427&loc=SL5780137-109256 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 45 -Paragraph 60A -URI http://asc.fasb.org/extlink&oid=96947427&loc=SL5780132-109256 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 45 -Paragraph 59A -URI http://asc.fasb.org/extlink&oid=96947427&loc=SL5780131-109256 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 45 -Paragraph 60B -URI http://asc.fasb.org/extlink&oid=96947427&loc=SL5780133-109256 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 45 -Paragraph 68B -URI http://asc.fasb.org/extlink&oid=96947427&loc=SL5498026-109256 + Details
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- Definition The portion of profit or loss for the period, net of income taxes, which is attributable to the parent. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04(22)) -URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04(18)) -URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03(20)) -URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688 + Details
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