XML 47 R35.htm IDEA: XBRL DOCUMENT
v3.20.2

Share-Based Compensation and Benefit Plans (Tables) | 9 Months Ended
--- | ---
Sep. 30, 2020
Restricted stock [Member] |
Share-Based Compensation and Benefit Plans |
Summary of activity of share-based compensation and benefit plans | ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | For the Three Months Ended | ​ | For the Nine Months Ended
​ | ​ | September 30, | ​ | September 30,
​ |  | 2020 |  | 2019 |  | 2020 |  | 2019
Compensation expense for shares issued under the ESPP | ​ | $ | 717 | ​ | $ | 622 | ​ | $ | 2,060 | ​ | $ | 1,831
Income tax benefit from compensation expense related to shares issued under the ESPP | ​ | ​ | 180 | ​ | ​ | 155 | ​ | ​ | 517 | ​ | ​ | 456
Compensation expense for restricted shares awarded | ​ | ​ | 392 | ​ | ​ | 351 | ​ | ​ | 1,094 | ​ | ​ | 1,038
Income tax benefit from compensation expense related to restricted awards | ​ | $ | 99 | ​ | $ | 87 | ​ | $ | 275 | ​ | $ | 258
Stock option [Member] |
Share-Based Compensation and Benefit Plans |
Summary of stock options | ​
​ | ​ | ​ | ​ | ​ | ​
​ | ​ | Shares | ​ | Weighted- Average
​ | ​ | (in thousands) | ​ | Exercise Price
Outstanding at December 31, 2019 |  | 1,635 | ​ | $ | 218.10
Granted |  | 162 | ​ |  | 389.99
Exercised |  | (251) | ​ |  | 157.51
Forfeited or expired |  | (19) | ​ |  | 298.31
Outstanding at September 30, 2020 |  | 1,527 | ​ | $ | 245.27
Exercisable at September 30, 2020 |  | 1,006 | ​ | $ | 199.31
Black-Scholes option pricing model | ​
​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | September 30,
​ |  | 2020 | ​ | 2019
Risk free interest rate |  | 0.90 | % | ​ | 2.34 | %
Expected life |  | 6.1 | Years | ​ | 5.9 | Years
Expected volatility |  | 26.1 | % | ​ | 25.0 | %
Expected dividend yield |  | — | % | ​ | — | %
Summary of activity of share-based compensation and benefit plans | ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | For the Three Months Ended | ​ | For the Nine Months Ended
​ | ​ | September 30, | ​ | September 30,
​ |  | 2020 |  | 2019 |  | 2020 | ​ | 2019
Compensation expense for stock options awarded | ​ | $ | 4,473 | ​ | $ | 4,590 | ​ | $ | 13,908 | ​ | $ | 13,709
Income tax benefit from compensation expense related to stock options | ​ |  | 1,123 | ​ |  | 1,143 | ​ |  | 3,492 | ​ |  | 3,415

X
- Definition Tabular disclosure of share-based payment arrangement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5047-113901 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
Name: | us-gaap_DisclosureOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure for stock option plans. Includes, but is not limited to, outstanding awards at beginning and end of year, grants, exercises, forfeitures, and weighted-average grant date fair value. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
Name: | us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of the significant assumptions used during the year to estimate the fair value of stock options, including, but not limited to: (a) expected term of share options and similar instruments, (b) expected volatility of the entity's shares, (c) expected dividends, (d) risk-free rate(s), and (e) discount for post-vesting restrictions. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (f)(2) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
Name: | us-gaap_ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_AwardTypeAxis=us-gaap_RestrictedStockMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=us-gaap_StockOptionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |